Just found out the hard way a rather unfortunate bug with the Forge and WvW weapons. I spent some badges and gold to buy three exotic staves from the WvW vendor – an Invader’s, a Berserker’s, and a Carrion – to forge and try for The Legend. There’s no distinction between them in the merchant UI or the item UI other than the stats. However, only the Invader’s staff appears in the Mystic Forge UI. The others do not.
They should either all work, or else state which ones work and which don’t. It was very disappointing to find out after I spent my badges that I had completely wasted 2/3 of them.