this is on old issue , when in pvp, sometimes bugg appears and any weapon shows as no grade weapon, here video proof
http://www.youtube.com/watch?v=bsnt_REY9Y4
(look at 00:50) after he gets knocked down, his weapon apperaance changes to a no grade dagger.
ALWAYS CHANGES TO the NO GRADE sword . so probably game engine has a default weapon id or smt that reverts too.
and here is topic, this bugg appeared since tauti updated, introduction of appearance engine, and never went away, present even now. would be great fix, because players think it s an exploit.