Claimh Solas is a monster re-created out of Alchemy Transmutations, appearing as a upper half of a demon with sword-like wings. It is an extremely unstable weapon, and a major threat to all of Erinn. The Fomorians were blinded by greed and performed the transmutation in order to destroy all of Erinn.
Claimh Solas is actually a sword belonging to Nuadha, and used it within many battles. It is often called the Sword of Fire, Sword of Light, or Sword of Fate.
Claimh Solas is known to make frontal sweeps, absorb health of others, create shockwaves out of darkness, and can even use Sword of Light which generates numerous piercing blades from its wings, dealing heavy damage.