Blade tape
There is a novel development of a leading edge tape that not only provides protection it produces a significant reduction in aerodynamic drag with consequent increases in lift and efficiency. You should PM the PPRuNe name "fdr" for more details. This guy has done an enormous amount of testing including evaluating the improvement in stall performance for an R22 (brave man). The data to date is sufficiently impressive that it raised significant interest in military circles as a retro-fit.
If you can't find fdr, PM me and I'll let him know.
Regards
Blakmax