They have only one unit type, so they will stand their ground and fight to the death, and they have Nihon bonuses and Bushido. As for the Naliar, they only have a rabble and militia as their fighting forces. It's a trap mission, to use your term.
But these Heckelian guys are all so suspicious, it's hard to tell who to side with.
And why are you so keen on the mages...?
Mages are supposed to be weak in general; if they can't defeat the Wind Lords, even considering their long-range spells, then from a strategic point of view, I think they shouldn't be very strong (and the description also suggests that).