Vayne is not the picture of an inspiring leader. He doesn't motivated others, make calculating decisions, or actually do anything heroic at all. But not person is born a leader, and it might be a little mean to expect that out of someone who is basically a little child with little experience with humans. Vayne's wishy-washy nature is a byproduct of his lack of both an upbringing and past interactions to draw from. All things considered Vayne did pretty well adapting to the crazy circumstances (and people) he found himself with at Al-Revis academy.

Vayne may be an alchemist, but his combat strategy screams warrior through and through. With brutally powerful swordskills to unleash upon foes (including turning himself into a giant blade), Vayne is a man(a) to be treated with caution. THe fact that he can take 3 turns in a row at will is probably another good reason for caution.