iirc, you can get seven points of wisdom with various dialogues and two more with a certain item. Some of those come pretty late, though. Check the gamefaqs site. There is a nice guide there that goes into more detail.
what are the values by which you can increase your stats the most, apart from investing stat points on level-up?
specializations, tattoos, dialogues...
I think you can increase your wisdom by a lot, but i'd like to know the exact number. maybe you can even hit 24 or even 25 wis by just picking up these bonuses, no?
Comments
http://torment.wikia.com/wiki/Wisdom
The hidden luck stat is very nice!