I said positive gameplay effect. That doesn't have to be beneficial for the character.
And I don't want to turn this into an attributes-heavy game. People should compete on roleplaying, the attributes are nice and should provide incentives, but they should not be too important.
Ok. It just seems that largesse, while an interesting aspect of chivalric life, does not easily find its role with game mechanics. Thus I am throwing in ideas and concepts that might give some flesh around the bones, or perhaps help someone else do it better than I do. Just to check if I have understood your purpose here, would something like this be positive for gameplay:
High largesse:
- Recruit more men (not as many as with high combat experience but still some)
- When you are unable to pay them in time, they wait for your payment more patiently, but still demand the full pay at the end OR
- With high largesse, you get a button in troop payment options that says "delay payment, promise to pay +50% wages later" which lets you get away with not paying them for a little longer, but if you fail to pay them full within a week, they desert you in bloc and you get severe largesse penalty hit.
- With very low (next to zero) largesse you get a discount in recruiting (perhaps in payments too), but a severe penalty in the number of men you get. This would help poor knights to at least get some men, and encourage to maintain at least a minimal level of largesse for the others. Donating just a few coins to a temple here and there could help you beyond that threshold, so it would essentially be a choice if you had zero largesse - if you really are that poor. And if you are, you would not be recruiting that many men anyway.
By themselves these proposals are not enough to make largesse meaningful, but it's a step. I am especially fond of the idea that zero (or next to zero) largesse gives penalties and thus directs the players automatically towards behavior that gains largesse, even if the gestures in themselves are rather symbolic. But for this it would need to be very easy to get past the zero largesse threshold and so that giving something like 10 gold to a temple should keep you safely above the limit for quite some time for it not become an annoyance.