AI should learn to use the merc feature correctly. Else I feel like cheating using it.
Illustration: I am a small count in Ireland. All counties are the same size and power, approximately. Now any time I have power with an other individual county, I just hire any band of mercs. My enemy has the money to do it but never does. That's it, all the uncertainty of war is gone, I found the one magical button for automatic victory! No risk any more in declaring war to someone roughly as strong as me! All is left is to get claims, the warfare part is just a formality. Now if these counties knew how to use their money to hire some mercs too, for defense but also if they want to attack me, that would make warfare a risky and uncertain business, as it should be.
Illustration: I am a small count in Ireland. All counties are the same size and power, approximately. Now any time I have power with an other individual county, I just hire any band of mercs. My enemy has the money to do it but never does. That's it, all the uncertainty of war is gone, I found the one magical button for automatic victory! No risk any more in declaring war to someone roughly as strong as me! All is left is to get claims, the warfare part is just a formality. Now if these counties knew how to use their money to hire some mercs too, for defense but also if they want to attack me, that would make warfare a risky and uncertain business, as it should be.