This is a modifier on the default critical strike chance (usually 0-2%). For example, a huge axe has a 1% critical strike chance. A supreme huge axe will have 1.3% critical strike chance.
Critical strikes only apply hits are enabled in PvP PvE combat. There are no known bonuses for rare weaponry on PvE serversand deal 150% of the original damage.
=== Horse Shoes ===