sword

where do chrystal weapons come from?

I think you mean crystalline swords... They drop only from HoH chests, FoW and UW chests that you get from completing quests.
There are other weapons that have a crystalline look: eternal shields, eternal and storm bows and ghostly staves. All those drop in UW.

Make a sticky for crystalines please.I saw about 20 posts this week about crystalines!

^^

There is Just scroll up and read the F.a.q.
If you want to keep something secret, just stick it on the top of every section