Thread:Spectral Purgatory/@comment-24776115-20150709071319/@comment-13526439-20150709171855

The Attribute of Dragonarms is literally 竜装機. 竜  竜  竜  竜  竜 The Very first Kanji. There, I found it. Also... From the Bushiroad Q&A

It states that Dragonarms can be used with Dragon Ein.