Increasing maximum Vigor?
The following abilities increase the maximum amount of vigor by +1:
- 2nd level of Fortitude talent (training tree)
- Both levels of Magical Vigor (magic tree)
- 2nd level of Destructive magic (magic tree)
Also, in chapther 3 there's at least 2 items which each gives +1 vigor when equipped. So, for a grand total, assuming you manage to collect it all and potion up you can end up with 9 vigor.