Rod of Lyssa is... quite powerful. Especially in a game like this where equipment is directly related to how powerful you are, usually.

I'd like to suggest some balance stuff for it so that it's potentially a bit harder to use and not highly game breaking.

Default: 50% chance of pickpocket working at maximum.
Requires mob to be unaware of the player's presence, making it a sort of stealthy item of opportunity to open with. Otherwise it will always fail.

Whether succeed or fail, it immediately makes the target aware of you and angry, giving them a bit of speed and strength temporarily but can make them more susceptible to damage (pretty typical rage effect combo in games). The target also becomes immune to further instant pickpockets with the rod so you can't just literally strip them naked for no costs if they have multiple items. But you could get a lucky drop on them and steal away a vital portion of their damage or survivability making it an easier fight and scoring it as loot.

The Rage effect can probably be a custom potion effect with the villager anger effect as the particles which has a similar effect of the speed and strength boost with damage susceptibility. The unable to be tampered with effect should be set some other way to make sure it can't get purged off using ars nouveau or some other mod with a purge effect to then allow more pickpockets in a roundabout way.

Subsequent uses of the rod just enrages the target even if aggro is dropped and you come back later. But if you never did pick pocket them at first, if you lose aggro you can attempt a pickpocket later. Pickpocket is only locked out when it's actually attempted.

Using rod on an already enraged target instead of stealing items off them increases the chance of an item from them to be dropped (random selection by slot), but also deals durability damage to the item that it touched.
So you can fish an enemy a bunch more times to loosen up their grip on their potentially lootable items then wreck them while they're raging to rake in the spoils. But if you do it too much you can run the risk of them raging so much their gear breaks.

The rod could also be made enchantable as a normal rod.
Lure could improve the area radius that items are drawn to it when the bobber is out and improve the chance of the pickpocket working at all.
Luck of the sea could improve the additional chance incremented on an item when fishing the foe.
Unbreaking, since the rod isn't breakable currently it seems, could possibly reduce the damage you accidentally deal to the items you're increasing the odds of dropping. Although I do suggest a durability be added to the rod. Even if it's something like 512 uses.