Vandals are crap, and they have a deliberately lower DPS to avoid killing planes and allow them to cast. But the daggers in the previous game completely destroyed all my air units.

Actually almost all the planes were killed by the vandals. They were not able to prevent the planes from firing but they shot it down after.

I think the bigger problem was building too many rogues and not having enough bandits. The glaives simply swarmed the rogues and killed them easily.