Jsk Wondrous Items:Warrior Priests Weapon

Source: Jnome's Secret Knowledge

Weapon (Any), Rare (Requires Attunement)

An apple-sized alabaster sphere that hides a secret. When a creature first attunes to this weapon, it takes the shape of any simple weapon or martial weapon that the owner wants. The weapon is an alabaster white with gilded silver accents, complete with an embedded diamond surrounded by celestial engravings and runes. This weapon can be used as a spellcasting focus for spells. When you make an attack with this weapon and kill a hostile creature, the diamond glows a soft silver. While the diamond glows, you can use the weapon as a focus to cast the Cure Wounds spell at its lowest spell level without expending a spell slot. When you cast a spell using this weapon and the spell uses your spellcasting modifier, you use your spellcasting modifier or double your proficiency bonus (whichever is higher). When you cast a spell using this weapon, the diamond stops glowing, and it cannot glow again for the next hour.