Legendary Weapon

Whenever a creature dies, you may put a quest
counter on Legendary Weapon.
As long as Legendary Weapon has ten or more
quest counters on it, it is an Equipment artifact.
It has indestructible, "Equipped creature gets
+6/+0, and {1}: Equipped creature gains your
choice of first strike, trample, lifelink,
deathtouch, or reach." and Equip {0}.