Feint is useless, not because the skill itself is useless it's because you'll never use it when compared to everything else you have along with the diminishing returns it has. It's a DPS loss, and a waste of TP compared to your other skills.

I always use B4B with Relentless Strikes and Hawk's Eye for really nice burst, and follow that up with Raging Strikes + Internal Release, the cooldowns just line up well that way.

Invigorate is a must have at end game, mainly due to the lengthy fights, and for Expert Dungeons, the AoE that you'll be doing and likely using Ballad for the healers mana or Requiem for the BLM damage rather than Paeon for your own TP.