Battle field value of the King

[Maloncanth]

Note that it is possible in large battles to give your king stars and your better general valor without putting the king at risk. Simply shove the king into the reinforcements pile and don't ever call him out. He'll gain any post-battle stars or virtues but during the battle, your general (presumeably better at his job than the king) will be in actual command.

As for the risks of getting your king captured or killed, it is generally negligible as the AI is not sophisticated enough to pursue an assassination strategy decently so long as your army isn't grossly inferior. It usually only happens when the king happens to be the strongest/only heavy cavalry on your side and the enemy has some lucky artillery.