I see lots of stats, abilities, and equipment revolving around faster recovery of Vigor, but no mention of increasing the maximum.
Are you limited to two points for the whole game? If not, does it increase through levels? Gear? Plot events?
The following abilities increase the maximum amount of vigor by +1:
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.
Maximum vigor is 6, even with items that should make it higher. I found this out when I had 6 vigor through the magic and training tree, then equipped the forgotten vran sword which has +1 vigor stat bu my vigor stayed at 6.