You're taking duels far too seriously. They're challenging 1v1, sure, but also slapped right in the middle of content that intentionally received over 100 ridiculously strong Actions and Essences on top of a Medal system for permanent player buffs. It's hardly surprising players eventually figured out the best way to melt them down.

If you care about challenge, request some ilv synched solo challenges that only use the players normal toolkit. Something like Endless Proving Ground or the Mage Tower from WoW. Bozja was never designed to be balanced.