I have 100 smithing with all the perks but it still doesn't let me upgrade my Dawnbreaker to Legendary condition. Anyone know how to make it legendary?

yea u need like level 200 smithing, get fortify smithing armor, gloves, a ring, and a necklace, fortify smithing potion too, then u can get legendary, happened to mehrune's razor for me so i reloaded did that and got a legendary dagger

http://www.uesp.net/wiki/Skyrim:Smithing - scroll down to the item quality table.

You do realise you can improve weapons you have already improved, if you have more skill than before. It's not a one time thing.

he beat me to it, do what he says and it should work, worked for me with one of the daedric artifacts on my warrior...

they really need to change this i wanted to have a truely legendary volendrung or mehrunes razor but then i found out i would have to dabble into witchcraft to do so...very disheartening.

all caps chill

They need to change the smithing system by reducing the effectiveness of improving weapons, they are to overpowered.

Improving magical item isn't 'dabbling in witchcraft' to you?

Damn, sounds like I'll need to get 100 enchanting and 100 alchemy then . Anyways, can I upgrade it to Legendary after I upgraded it to Flawless?

Yep.

You don't need all that stuff. I used gear I bought from vendors and a simple potion bought at an apothacary shop. You just need a decent ring, necklace, and gauntlets that have at least Major smithing on them and a 30% blacksmithing potion along with 100 smithing. That's what I used to get mine to Legendary. Getting 100 enchanting and alchemy is going way overboard.