The bracelet has five charges. After all five charges are used, it turns to dust. Players can use a charge of the bracelet to become immune to damage caused by Revenants for one minute, as well remove their aggression for one hour. The removal of aggression helps Revenant farming considerably as they won't cast spells on you before you attack one, and then only the one you attack will fight back. This stops Revenants stealing your combat focus while in single-way wilderness combat mode and removes the added damage of magic spam while in Multi-Way combat mode.
The bracelet also keeps you from being skulled when entering the Abyss. Each time you enter uses up one charge.
Alchemy spells will always provide the same number of coins when used on the brace regardless of how many charges it has left. Many players use four of the five charges and then sell the item back to the grand exchange or cast high alchemy on it to recover most of its cost.
An additional ability was added to the brace for it to protect against Revenants' teleblocks. If a player came under the effect of a teleblock cast by an NPC then, by equipping the brace, they could teleport despite the block; providing that they are below level 20/30 Wilderness depending upon teleport method used. However, if instead the teleblock spell was cast by another player, rather than by an NPC, then equipping the Forinthry brace did not cancel the spell's effect and the wearer remained teleblocked. This effect of the brace was determined at the moment the player attempts to teleport. Equipping the brace did not ward off or cancel the teleblock spell itself, it simply inhibited the spell's effect while being worn. So, a player needed only equip it immediately prior to teleporting. If they unequip the brace whilst teleblocked then the spell's effect was restored for the remaining normal duration (5 minutes from cast).
After the Wilderness and Free Trade update, the ability for the Forinthry brace to repel Revenants and give a temporary immunity from their damage was added. The anti-teleblock ability was removed, as Revenants no longer teleblock.