I was able to scratch build some bangles with the same large bevels as the AC2 belt buckle and bracer. I used a base, in this case PVC pipe, put a styrene ring around the PVC pipe to guide the height of my bondo when I applied it. Then I just sanded it to shape and I got a really nice bevel.
You could do the same by cutting out the assassin's "A" shape then putting a styrene guide on it, applying bondo etc etc. The fine details can be done with puffy paint oddly enough if you so desire, or apoxie sculpt.
Finally just strap it/glue it to some vinyl or leather with E6000 and you'll be right as rain. I attached some articles that detail some of the things I've been talking about.
Puffy paint detail and bondo/styrene buildup.
Xiba bangles (bondo/styrene buildup)
Rin sword (bondo buildup)
As you can see bondo and puffy paint paint very well and can get a good metal effect if you so desire.
Edit: Playing AC3 now and it's bringing me back hardcore to the AC franchise. Loving it!