An idea to improve the use of monks for healing - provide a modest (10-20%) boost to healing speed if there are no enemy units within their healing range. This will significantly improve campaign experience and also make monks more viable in RM games.
Or maybe unit that getting healed will have less armor than normally as you remove armor to apply bandage.
With this, You can just buff healing a bit better but add condition that healing during fighting is worse down to normally we have.
Monks are a fairly strong unit. The ability to convert a unit (such as a knight) is pretty potent, particularly since a monk will often pay itself off with just 1 conversion. For example, a knight is more expensive than a monk, and is a common monk target. If you convert 1 knight, you remove a 135-res unit from the opponent and gain it for yourself. It is possible that the knight will be damaged when you receive (making the value worse comparatively), but the monk also heals (which can also provide insanely good value). The swings are even worse with siege weapons. The only downside of a monk is that they are micro-intensive, which keeps them from scaling. Most unit blobs are more than twice as powerful when you double the number of units. That’s not really the case for monks (which quickly become too unwieldy to use).