Can it change the way weapons are held? Say I have a weapon which would look better if it was held as a melee weapon rather than as a pistol, would it be possible to do this in the GECK? Is there an option of how the weapon is held, e.g. pistol, melee, rifle etc...

Cheers

If it is (simply) possible, I'd guess that would be under the Art & Sound section of the weapon in question. There are drop down lists where you can pick animation type, attack animation, hand grip, etc. Whether altering these while leaving the other stuff at default would make the weapon look really odd during combat (vs. posing) as a consequence, I don't know. Experiment & find out?

Duplicate thread with more information at newvegasnexus. Almost always, posting at newvegasnexus will get more/faster replies.