A rune mace is a mace made of runite. It is currently the fourth-strongest mace in the game, only to be surpassed by the Void knight mace, Dragon mace and the Tzhaar-ket-em. The only requirement for this mace is 40 Attack. It can be made at level 87 Smithing using one Rune bar.
The rune mace can be purchased from Scavvo’s Rune Store in the Champions’ Guild for a price of 14,400 coins after obtaining 32 quest points.