Grune the Destroyer

This idea came about while watching the Thundercats episode The Ghost Warrior about Grune the Destroyer. Grune was a former Thundercat who was banished to Third Earth after betraying Jaga. He wreaked terrible havoc on that planet until his death, after which he was magically sealed within a tomb.

In the episode, a pair of gnomish creatures happen upon the tomb and violate the magic seal, freeing Grune. While inside the tomb, they notice it is filled with nothing but broken weapons. In particular, you can see two or more broken morningstars (Grune's favored weapon) atop the stone slab that seals his final resting place.

The idea this sparked was thus: a champion or avatar of the god of war and battle is unstoppable in combat but he can be warded off by broken weapons (perhaps an old symbol of a god of peace, his philosophical opposite). This ward is not foolproof and it requires real sacrifice. For example, if the PCs came face to face with the champion and threw broken arrows across the hallway while still wielding magic longswords, maces, and rapiers, the champion will take little pause in proceeding (though a merchant encampment surrounded by broken weaponry may well remain safe). If the champion were to be raised from the dead as was Grune, then the original method of his defeat was the sundering of his weapon in battle (the champion himself having never known defeat by force of arms). If the champion were a new development, then the discovery of his weakness to broken weaponry could lead thoughtful players to the conclusion that sundering his weapons would further weaken, if not outright defeat, him.