Collect all the Titan Tablets, Priest Amulets, and Emporer Coins and
offer then at the appropriate pillar to unlock the Weapon Challenge
arena in Elysiam. You can earn different weapons by completing the
various challenges in Elysiam:

Annihilation - Clear Axe Challenge 4
Invictus Gladius - Clear Sword Challenge 4
Olympus Cleavers - Clear Gauntlet Challenge 4