Sapping Seed

This weapon has 2 charges; whenever it reduces
a creature of CR 1 or higher to 0 hit points, the
user can spend a charge to instantly kill it and
have the weapon gain 1d6 energy.
As an action, the user can spend any amount of
energy to restore an equal number of hit points
to themselves of a creature that they can see
within 30 feet.
Constructs and undead are immune to these effect.