The soldiers and knights are kind of worthless no?
Soldiers help screening small flies, which help a lot.
Knight is as helpful as insurance is to accident. That is, entirely worthless to actually avoid or solve the problem, but helpful at reducing impact if that problem is not avoidable/solved.
What is actually worthless is the noble, which don't directly help with any essential tasks. (All tasks they did could be given to other.) The only job required from them is to claim the success, because the kingdom wouldn't let commoners claim it. He's there to prevent the human problem, not to solve the monster problem. (He did help, but not as a noble.)