You can definitely resharpen bronze. The castings are not perfectly sharp, the edges are further worked (and can be hammered and work hardened). I don't think you can redo work hardening indefinitely but you can a bit and can scrape and grind and hone repeatedly. There are (or were last I looked) some people supplying cast blanks these days for re-enactors to try sharpening up. Always wanted to try that one day.