4 if you have the massive funding for unfunded, 50 if you don't plan on using Rigbol and unfunded, 100 + 20dex in equips if you do plan on using Rigbol. I'd recommend 50 just like FrenchConnexUK said.
Also, think of Blast and ACB as Slash Blast and Power Strike. ACB takes out mobs like Slash Blast while Blast is your hard hitting attack for bosses and lone mobs like Power Strike.