Probably a lot of pll don't know about it, and I found it only like today. I'll put a link to one site which says it all. It's not my site.
(might be outdated, check wiki for 100% right combo: http://wiki.guildwars2.com/wiki/Legendary_Weapon)
http://segmentnext.com/2012/08/30/gu...where-to-find/
In 2 words, if you want cool weapons aka legendaries you need to pick 2 specific crafting disciples to craft them... I made this topic so pll can see and don't repeat my mistake. Thanks.