The obvious question is: what does this build offer you that, say, a pure pally Vanguard does not?
Pros:
- 7 extra feats from ftr 12
- Mana-less healing from One Spirit + temp HPs from Vampiric Bond + barb heal amp to boost survivability
- Depending on AP spread, some DPS bonuses from barb which don't depend on Rage
Cons:
- Severely AP-constrained: at a glance, you'd want 38 APs OS, 24+ APs VG, 13-24 APs SD, and 8 APs WP, which is 83 to 94 APs right off the bat, so...well, good luck with that.
- One Spirit can only be used once every 15 secs - that can feel like a really long time when you're a tank...
- Lose +10% atk speed & +5% doublestrike by not being pure VG; lose +10% doublestrike and crit bonuses from not having Zeal + Holy Sword. I'm pretty sure that's a bigger DPS loss than anything you're gaining from barb.
It's an interesting concept, but in practice I don't think it would work out too well. It could be a decent split for a ftr PL option, if you gave up on tanking and just did a straight DPS+some heals build: 38 APs OS, 23 APs Kensei, 4 APs WP, 14 APs FB (Supreme Cleave + Frenzy), 1 AP human (Dmg Boost).