Runes can be put on any armor. You won't find any pre-sear, but there are rune traders post-sear. Anyone can use them, but you can only use the ones of your primary profession. There are 3 "grades" of runes: minor, major, superior. Minor adds 1 point to the attribute, major adds 2 points (but you lose some health, think 50?), superior adds 3 points (also lose health, think 75?).