http://www.ebay.com/itm/VINTAGE-BRASS-WIRE-STRIPPING-TOOL-NAVY-/261041454872?pt=LH_DefaultDomain_0&hash=item3cc7487f18

It seems to be what is claimed - a cable stripper...

Bronze just seemed like a strange metal to choose for an edge tool.  OK, non sparking, but where is that needed?

True, but the insulation cutter itself wouldn't be bronze - just the holder/handle.

Below street electrical manholes often accumulate methane gas.....
(vegatation falls into them and rots, nearby sewers leak, gas mains weep...)

Today we have meters to detect it, but back a bit it was generally safer to use non sparking tools when working in manholes if possible...

If you look close there are steel insert cutters opposite the V.

The tool is clamped onto the wire and wound down to the end in a spiral so the insulation can be wound off in a single piece.  It was originally designed and used in the era of fabric covered rubber insulation which in the best of days was a pure beach to strip.

The tool definitely predates plastics, and Bronze is a very common material in marine environments.

>Bronze is a very common material in marine environments.

Yep.  It's not about sparks, it's about rust, especially around salt water.