Source: Baldur's Gate - Descent into Avernus

Wondrous item, rare (requires attunement)

While you wear both of these steel gauntlets, any nonmagical weapon you grasp with either gauntlet is treated as a magic weapon. As a bonus action, you can use the gauntlets to cause magical flames to envelop one or two melee weapons in your grasp. Each flaming weapon deals an extra 1d6 fire damage on a hit. The flames last until you sheath or let go of either weapon. Once used, this property can't be used again until the next dawn.