Demetri is one of the best fighters, intellectually speaking.

Imagine him vs Zara. It'd be close, Very close. Her agility and feints vs his deductions and intelligent counterattacks. 5.5/10 victory goest to Demetri, but it would be down to the wire. It doesn't apply to their real life actors, as Zara's played by someone who knows martial arts in real life at a high level, whereas Demetri's played by someone who knows Krav Maga but it's never specified how much, so presumerably at a lower level than his opponent.