Have it look like Sephiroth's masamune on FF7 and have a collection of severed heads hanging all around the players belt.
Super attack speed. (10-20%)
Chance for 50% lifesteal (5-10% chance)
Chance for 300% crit damage (6-8% chance single target spells, 2% for aoe or multitarget. If this procs the player gets a free guarenteed crit)
1 main stat roll
Your critical hits display a huge splatters of blood that shoots halfway across the map at high velocity.