I thought of an idea for a final tier weapon and I wanted to share it. Not sure if it can be a melee weapon or a throwing weapon. I classified it as a melee for simplicity
Final tier melee weapon - Kingdom key from kingdom hearts
Left click to initiate a "strike raid" tossing the sword as a horizontal piercing projectile in the direction your facing and, returning to the player like a boomerang.
You can catch it like normal or you can parry it back out, multiplying the damage for each successful parry. (30 damage base, first parry doubles to 60. Second doubles to 120, third to 240 etc.)
The weapons return speed could be a bit slower than throwing it initially so the player has time to set up a parry.
Alternatively instead of throwing the weapon itself you could, throw a spectral version of it instead so the player could still use it as a melee weapon.