Heavy (3.5e Equipment)
From D&D Wiki
"You grab the greataxe, hefting it up, but, not expecting the excessive weight, you lose your balance and fall flat on your face. The greataxe is much heavier than it seems."
Only two-handed weapons made primarily of metal (such as a longsword or a greatsword, but not a quarterstaff) can be enchanted with this enhancement.
When a weapon enchanted with heavy is used with two hands, the damage from your strength bonus is multiplied by 2 instead of 1.5 and because of the sheer weight of the weapon add 2 damage die that the weapon already does. However, any weapon enchanted with heavy also has a strength requirement to wield correctly of 19 or higher or, if it already has a strength score requirement to wield, the minimum strength score requirement is increased by 2. Additionally, there is a minimum requirement of 18constitution. Finally, the weight of the weapon is increased by 100%.