How to win with a “weak” Knight?

Unfortunately, this is the first army that Lightning and other nasty spells are directed at. So, very often, Paladins or Crusaders, who are not easy to create, appear once or twice, and then they are simply gone. In general, the strategy against a Knight is elementary. A Warlock with, say, 5-3 stats, a couple of Gargoyles, and three Kentauros can deal with him. If the Knight is slow, the Warlock can hit him with Lightning two or three times and then run away. Then, a Beaver with his army arrives, and the Knight hero is no more. Playing as a Knight is worse than playing as a Necromancer, especially on King difficulty. Sometimes, Swordsmen are not even built in the first week, the army is slow, and if the Castle is located somewhere in a swamp, it's a complete disaster.