Some thoghts:
One of the worst skills in the game. It doing [about] nothing (Because Blood Bath do more vs defensives, much more).
I disagree. This isn't a one or the other sort of discussion. Training Blood Bath doesn't preclude you from also taking Flurry of Steel. One can also make the argument that Blood Bath isn't that useful against offensive glads since those fights rarely last more than a round or two making Blood Bath fairly ineffectual. The usefulness or uselessness of a skill varies on a glad's build. Some builds will benefit more from certain skills and less from others.

I'm of the opinion that managers have just scratched the surface of the new school. There were a number of complaints on the boards regarding Shadow glads being weak, and now I see two in the top 10 of BG because someone decided to put some effort into creating competitive ones. I suspect Slayers are in the same boat. Time will tell.