If you are specced Advanced Prototype you would be using this ability so you can Railshot. Now for the less obvious part. At lvl 50, fully talented with 15% more bleed and 6% more direct damage (which is a total of 5 talent points btw) this ability does 146-180 kinetic damage (which is reduced by armor) and a bleed effect for 239 over 15 seconds.

At lvl 50 in semi epic gear I'm running with 1200 Aim atm which puts the ability on 634-667 kinetic dmg + 955 over 15 seconds.

Neither does the bleed effect stack if you stab something repeately.

Clearly the nubmers here need some looking into. Why bother using Retractable Blade and railshot when I can just spam a few Flame Bursts on thos globals instead.