The battle, in the beginning, was following the trend of Lex gaining overwhelming momentum. No matter how Daekol tried to fight back, his attempts were too feeble to affect Lex. His ultimate weapons, which would have otherwise greatly affected Lex, only barely harmed Lex.
On top of that, Lex's own attacks kept pushing Daekol to the point where he genuinely felt like he was in danger. His techniques were seen through, his defenses failed him and his life was in danger. It wasn't a fair fight at all.
Yet the moment Daekol began to use his system, the momentum of the fight changed, and quite drastically at that. Accruing debt suppressed Lex on a fundamental level. The fact that Daekol was his debtor automatically made all of Lex's attacks against him weaker by a fixed and undeniable 20%.
