Recently our GM has given the party an item that could easily break the game for the rest of the campaign. We were given a Sap of Healing that deals 1d6 damage and after successfully hitting a target heals the wielder 1d6 HP as well. There are no limits on HP healed, nor any conditions on how the item heals (such as no healing provided from undead or constructs). This would mean, with a little bit of cheesing, our characters will always be at max health between encounters.
As a player, I believe an item like this is tremendously overpowered and shouldn't exist. However, I don't think anyone else in the game feels the same. The GM intended this to be a 'gag item' and I don't think he realizes how this will affect the game. I've not talked to the other players yet but when the weapon was introduced, none seemed to think the weapon was overpowered. None of the characters have any disapprobation towards the weapon.
No one in the party has laid claim to the item yet, and it is currently in possession of my character, the wizard, since I was the only one who could determine its properties. I had made a spellcraft check of 37 (Rolled 18, Skill + 9, Identify +10), and determined the weapon was not curse or hiding any other properties. I've talked with the GM and suggested that it be modified to be a "Vampiric" weapon or to put some sort of constraints on the amount of healing it provided so it doesn't trivialize the game. For reference our party is level 2 and consists of a Slayer, Fighter, Rogue, Monk, Magus, Arcanist, and myself, the Wizard.
Am I overestimating the power of this weapon? If not, what can I do to prevent this weapon from breaking the game?
The item was originally a sap and dealt nonlethal damage, but could be used to deal lethal damage with a -4 roll. The healing is not a drain ability, so a character striking themselves with the weapon would still benefit from the heal. Due to magical healing recovering both lethal and nonlethal damage, the average roll of 1d6 (3.5) for heal would cancel out the average nonlethal damage (3.5) but also heal an average of 3.5 lethal damage. Thus we could restore an average of 35 HP per minute using this item.
The GM later modified the item so that it could only do lethal damage, but there's still nothing to stop a character from gathering chickens or raising zombies for us to use as cannon fodder to sacrifice to the sap.
My GM introduced an overpowered item to the party and how can I prevent this item from breaking the game?