Staff of Battle Magic Feat

Elemental Absorption  The absorb elements spell cast by the staff is used to replenish charges rather than providing resistance to the elemental damage type, and additional damage on the next melee attack. The number of charges replenished is equal to the total of the d6's rolled when casting the absorb elements spell. The charges needed for casting Absorb Elements are expended before new charges are added. If the charges gained exceed the current maximum number of charges, the staff permanently loses 1d8+5 charges from the maximum number of charges the staff can hold, and the number of charges the staff is holding is immediately reduced to the new maximum. Creatures with truesight will see a vivid blue glow that illuminates everything within 1 mile as the excess charges are dumped; Creatures who lack this sense will see nothing. Creatures and items within 500ft experience a large increase in static electricity. After this overload, the staff is unusable for 1d4 hours.

Dimensional Shunt  For ease of storage, and to keep the wielders hands free, the staff can be stored in a pocket dimension. Once stored the wielder is still attuned to the staff, but no spells can be cast from it. Spells already cast that require concentration persist. The staff can be both stored and retrieved as a reaction, a bonus action, or as one of the wielders attack actions. If the weapon is thrown as an attack action, it can immediately be stored or retrieved to the wielders hand. Outside of combat, the staff can be summoned and dismissed at will. The staff can only be summoned to the wielders hand, but it can be moved to the pocket dimension if the wielder is within 90ft of the staff. The wielder must have a free hand to summon the staff, or have gained a feat that lets them cast spells in combat (e.g. War Caster or Spell Sniper).

Thunder Strike Once per turn upon a hit, the staff can expend one charge to deal an extra 2d8 of thunder damage. The target must then succeed on a Strength saving throw, or be pushed away from the wielder up to 10ft.