Is invisible blade really worth it when you have enforcer and shatter defenses? How would it be better than just full attacking and then just normal vanish after? I suppose it saves Ki, but you probably have a nice amount of Ki by then. Plus, things start to have more methods of detection at this point, and it only gets worse from there.
Maybe a diff trick would be better.
Also, I feel that overall, it's worth going for Medusa's Wrath instead of TWF chain with this build. Little more utility...one fewer attack, but two more at full BAB.