Assuming your accuracy remains rather consistent, this Scythe can amount to an increase of anywhere between 5-8% in critical hit rate. The 13th hit CAN miss, however when it connects it's guaranteed to critical. Should also be noted that the "counter" for the Scythe does not reset when unequipped or when zoning.
Decimus asks an interesting question (not sure why someone would rate him down for it...) The hidden might proc during level sync, someone would really need to check it out lol
