each of the vincent jobs has its purpose. warlord for trigger team, bzker which of course everyone knows bout it, gladiator for cc control in arena (but lately vin gladiator's usefulness has gone down alot) and vincent dragoon which in later game content you will know how important he is (one of the stun master apart from freya dragoon)
but if you have some other units like shizu which can replace as trigger, the only vin job that is really important is bzker and dragoon. Warlord and gladiator is more easily replaceable by other units.
I have an ares zerk, my trigger units are currently GR Kane and GR Cybella, plus aura refresh Kai (it's so random haha also, thieves hate me) I forgot what faith my new Vincent is (I'll check)
thanks for the info!