Flurry of Steel

[Kreegan]

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.

Shadows got a buff at some point and Shadow Dance actually started working - before that it was just a mean to get the two high tier activated defensive skills trigger more often. Usually such big shifts on some build's efficiency have more to do with Nate's stealth updates than with some manager's sudden stroke of genius. Let's not forget that all Shadows in BG are also HoL Mk2 slaves.
As for Flurry of Steel - its problem is that it sits at the top of the Slayer tree so you need to take at least 4 activated skills to get it. Which means that your gladiator will act in a pseudo-random fashion way too often. Personally I don't like having no control over what the gladiator does and usually that's what you get with 100/100 Slayers.