AWA 2 is fine for most playthroughs, but AWA 3 gives you a tiny defense boost as well as sets up you nicely for the Peaceful Ending.
IF you are going for the Peaceful Ending, you'll need AWA 5 to find a key item (see Wiki for more on that). However, there are plenty of +2 Awareness items (amulet, googled helmet). So even if you're going for the peaceful ending, having AWA 3 is more than enough (just equip the item when you need it).