Greatsword of Artorias

Equip {2}: (Equip this to target creature you
control; you can only do this any time you can
cast a sorcery.)
Equipped creature gets +2/+3 and has: "When
this creature attacks, you may exert it. If you do,
it gets +1/+1 until untapped."
"Makes you feel stronger, doesn't it?"
-Knight Artorias