Increasing Valour for Agents

Hi guys just trying to make sense of how valour advances for Assassins, Emissaries, Priests, and the like...

I gather that in very general terms, if they succeed in their mission, they are possibly going to increase in valour....but....

I have also noted that this isn't always the case (particularly with emissaries). Is there any rhyme, reason, or formula as to how these increases are awarded?

What TW game are we talking about? I asked the same question about MTW in the main hall, it should still be there.

Since there is a mention of priests, I suppose you are talking about M: TW.

Here, check this link:

https://forums.totalwar.org/vb/showthread.php?t=65742

Thanks for pointing me in the right direction guys - "bamff the myopic" rides again!