The razorback gauntlets last for 100,000 charges of combat before degrading to nothing - they cannot be repaired. Once equipped, they instantly become untradeable, even if they have not been used in combat.
Upon death in the Wilderness, a fully charged pair of gloves will drop 25,000 coins. The number of coins dropped decreases linearly with the charges remaining.
When in Raids the drop rate of razorback gauntlets is 1 in 500 for both Airuts and Beastmaster Durzag.