It's not as easy as some believe. The location isn't suited to Duke's charges so straight away he's been neutered a little bit. In the CW vs Keisha neither side could really dent the other and even though Duke had the huge numerical disadvantage, it was on a plains. Duke also didn't have to defeat Zhao either - he just had to hold out and prevent being wiped out. Here, he has to actually take out Keisha/enough Zhao soldiers.
If we're to take their styles into account as well, this location definitely helps a spider who lays traps ahead of a lion who needs to be able to see to act.
Duke wins though. High difficult maybe. He's a level above Keisha.