What is Training and how can you counter it?

I don't see any problems with this training; it's very expensive, and the Knight won't have enough money to upgrade everything, but in the end, you're not playing against Bill Gates. The only time the training really hindered me was in the "Triumvirate" mission, where Isabel created 600 paladins. It's also possible to fight against legions of skeletons. I think the most difficult thing is fighting against an Experienced Dwarf, because he has two types of magic: regular and runic, which are significantly cheaper than the training.