The belt works in arena, yes. But I am not sure it is worth using it, which implies giving up the great stats from a pvp epic belt.
What we say is basically the same: engineering has its uses for pve (cables, repair bot, etc.) and some use for pvp (googles, belt, etc.) but the pvp side gets obsolete at some time.
In my eyes, it's not worth leveling engineering JUST for pvp. I'd rather recommend leveling up enchanting for the ring bonus that nothing else can replace as of now.
I point it out because the OP says he'll pvp, mostly arena (in arena, most of the pvp goodies will not work; for instance, I would definitely use the frost nova bombs if I could, but I'm pretty sure they won't work in the arena).
nostra
Edited, May 14th 2008 5:24pm by nostraaa