I added the mesh I'm using to the downloads on the nexus page for my mod.
http://skyrim.nexusmods.com/downloads/file.php?id=11177
"Powershrine_nirnroot_nif" - the miscellaneous file.

You can put the nif file into:
meshes\plants\floranirnroot01red.nif
or
meshes\clutter\powershrines\powershrine01\warriorstone.nif

Probably better to use the second one.
Then you can coc to "guardianstones", and one of them is a crimson nirnroot!
You can activate it like a normal guardian stone, and the animation will play. But I have no idea how to get it to be on by default, or how to get it to loop...

Ducey, I didnt get a chance to check it out last night.
Looking at it right now. So far it looks like, for amulets/hoods/helmets, there has to be some attachment to the head. There is a NiNode with a value on the Head. Also in the NiTriShapes of the Amulet in your AA file there is a DismemberSkininstance. Im kind of playing with that now, adding to the NiTriShapes of the Node of Glow etc.. No luck so far, I get the feeling that our problem with the light not showing up has something to do with this.
I did try an attach our Dawnbreaker node to the NiNode that has the Head value but the nif complained that it was the wrong Block type for that kind of node.

Turn_on_a_Dime
That is some good progress. Ya have done some animation stuff here and there but I plan on learning the innerworkings. Ill start with your light beam. I do remember that in my FO3 project I did have to do some scripting, but Im sure there is a way round that. It might be that we will have to make a new fx animation and attach that to the mesh that you place. That way it will always be in play. We can do this either, like placement ontop of your object (like fog or beams of light dust or sunbeams) or we can try and place it as part of your mesh itself(which is what Ducey is trying to do as well)
Now that I think about it, you can probably bring up the animation and the root in your nifskope, add those strings, then add the beam node. That might work. The only problem Ducey and I are having with that technique is that our animation is not showing up while wearing the object with the attached animation. All is good for the model though. Its definately worth a try.

Turn_on_a_Dime
I took a look at your nif and researched into the ninroot set up. Here is what I found so far.
It seems like you can solve this without having to manipulate the nif. Every ninroot has that glow, ya know. That glow is scripted to appear and disappear depending on if the ninroot is there or not. You could manipulate the glow effect that skyrim calls for and replace that glow with your beam of light. All it seems is that you would need to create a new light model using the lightbeam nif. I am trying that right now to see if this will work.

II Ducey
Still stumped. So far I have tried to move up the NiNode block of the Dawnbreaker above the Head node with no effect. Also Tried to attach the DismemberSkinInstance under the TriShapes of each light model (NiNode>NiBillboardNode>NiTriShape>...) with no effects, but it is the proper node type.

In the CK I went ahead and made sure that all AA were using the light as well as the First Person, which the orginal CK item does not. All to no avail and no change in our effects for the Player's third Person Circlet model/mesh effects. Ill keep playing with it and see what I can do. I cant figure why the effects would show up in every instance of the rendering except the Thirdperson for our Player.
It could be that the 3d 'skin envolope' does not have that large of a zone to include our added effects, but somehow I think that this is not the case. Any luck on your end?

Turn_on_a_Dime
Replacing the GlowAcivator does work to change the effects. I added a lightshaft over the Ninroot with this new glow effects(Dungeons\Dwemer\Animated\Observatory\FXDweCenterLightBeamObservatory.nif), overriding the orginal form as to not create a script. There are a couple of draw backs though.
1. The ActivateGlow is connected to all Ninroots (the Ninroot script does not care if the effect is on a reg ninroot or crimson one) Not sure how to fix this without scripting.
2. I could not find the particular light beam isolated from the PowerShirne as a nif. This can likely be solved by taking away the actual shrine in the nif and saving it as more of an FX or light beam. On the other hand it might cause more problems if the nif is connected and refuses to work without the Shrine, which is likely to be the case.

My suggestion for this would be to manipulate a current nif of a lightbeam already isolated and in use to replicate the same effects as the powershrine lightbeam using the transform option in nifskope. Then replace the Activate Glow nif with your new lightbeam nif. This would give you the same effects for the most part.
However you will still have the problem of having all the ninroots having the light beam. A possible solution to this without having to script is to override the reg ninroot in the CK with one that does not have the glow script or possibly a tweeked script leading to another type of glow nif.
Also, have you tried using the Crimson ninroot as your base model and moving over the light beam effects instead of replacing your shirne with the Crimson ninroot? This might solve all the issues in one move.

None whatsoever. The reason I don't think its the skin model thing is because even the World Model won't show up with the light. That theoretically doesn't ever interact with the Player model.

The light is showing up in every rendering window in the CK for me. The world model too. Im using the gound object for the world model though and I did create a new nif for that. I didnt that it had much relevence to the wearing model though. Either way it still has not shown up on the player when wearing it.

I did find something interesting though. When I carried (like when you hold the 'take' button on it and you 'grab' it)it around the light showed up in both third person and first person, but the light kept flickering on and off depending on which way I was facing. In one area the light stopped for on whole side 180degrees and in other areas it was spotty when the light would turn on and off. This on/off flickering happend in both third and first person view. Might be a clue as to why the light is not showing up while wearing it. I went ahead an watched some videos on importing armors since this is very similar but didnt find anything relevent to this particular this problem.

Hmmm. Interesting.

In any case, I am trying to make a crown out of the crown of barenziah (in case we never get this halo idea off the ground) and I've made it the right size, translation, etc. and it renders when the character puts it on. But the problem is it doesn't track with the player's head, it just hovers in place roughly above them. Do you know how to fix this?

The light flickers on and off depending on whether it is in motion or not. Sometimes it is on in motion, though when it goes off, if I wait until it settles, the light comes back on. I think the reason the light is staying off on the head is because the person is in constant motion. It always seems to happen when I am around other light sources or pointing toward them. I also found that in the 1stpersondawnbreaker there is an extra TriShapeNode. I added this but it did not seem to make much of a difference to the issue.

I get the feeling that the crown problem is the same as the light problem. Both are not tracking the movement with the head properly. When the light tries it goes off, a nonlight/fx model just stays in place. Early on I had the same problem when replacing the Torch01 nif with other nifs. Whatever I would replace the torch with would just remain at the feet and slide accross the ground. The object would be static for the most part but connected to the player.

It is a billboard node. Is it possible thats it's rotated such that we can't see it?

Ahh. So a billboard node is just a 2d object that the effects can only be seen from one side and not the other. Then perhaps we can create two of those mesh/nodes containing all the dawnbreaker effects and pose them so their 'faces' are always showing.

There is a huge chunk of information lacking that is crippling my progress on many many fronts of my mods. This is fairly frustrating. I It would really help if there was some sort of chart with nodes defined and how these nodes are connected to eachother.
From what I gather, its a lot like any other kind of program.

NiHeader calls all the functions to use in the particular nif.
Then these functions call each value. (like returning value)
Sub(children)functions define different aspects returning values to the parent functions.(with most variables unknown to us which is a huge delema)

So I take it each 'type' of nif, be it lightfx, weapon, clothes, clutter requires a particular set up to get the results created in the nif.
I think what I need to do is just break it all down and practically write my own manuel for this. Ill Keep tinkering with your circlet.

If anyone else has any information on nifmerging we would be most greatful for any input on anything that can be offered. Successes and failures of attempts are very welcome here.
Tips and tricks on merging effects of different 'types' in the CK would be awesome too. I know that a lot of things can be merged within the CK so good 'goarounds' are awesome.

The Back to back billboard worked. The light never flickers and stays on now, but still refuses to come on when Im wearing it.

Thank you very much for your help!!
I have actually tried adding the light beam to the nirnroot, the reason I was adding the nirnroot to the shrine was because I couldn't cleanly transfer the entire animation stuff. So it worked better when I did the rather simple mesh replacement of shrine->nirnroot.
I do intend to just add whatever sort of light beam I can get to the nirnroot itself, so there will be no problems with the glow mesh. Furthermore, the scripts on the glow are buggy (don't always clean it up properly), so I wouldn't want to be using it anyway ...

What I will do for now is see if I can disconnect the light beam on the shrine from the animatio nthat controls it. It won't be as pretty if it's not animated, but I can deal with that later. It will be release-ready!

Is http://skyrim.nexusmods.com/modules/members/index.php?id=714579 your nexus account? And do you have a steam one so I can credit you for your help?

Edit: Good luck with the light on the crown!

Ya that is my Nexus account and my steam account is under Marbaus also. I glad I could help.

Its a shame that the glow script is buggy. It would have been a good starting placematt for the light.

Found this:

http://cs.elderscrolls.com/index.php/NifSkope_Comprehensive_Guide#Scene_Root_Node

It hasn't been updated since the release of Skyrim, but it does seem to help give leads to any issues that we might have in the future.

Ducey, take a look at the 'Prn' and "Scabbards Are Only the Beginning" spot in that guide. I think that the node might need some sort of attachment to your crown and halo light. This might be what is failing it when wearing it and moving with the body properly.