So I have an idea for a magic item for my death cleric player and wanted some feed back on whether or not it sounds balanced and a good idea. So the basic idea is a staff that can be used to attack a creature and store the taken hit points to be redistributed to another party member later.

It would have the stats of a quarter staff (designed this way because my player uses a war hammer and would have to do less damage to get the effects) that would count as magical for overcoming weakness when gathering Hit Points. It could store up to double the players Cleric level plus their wisdom modifier and would require attainment. Any feedback is greatly appreciated!