Generals losing stars and sudden routing

[caravel]

I have two questions but I put them into one thread as I suspect they are related to generals' personalities.
1. I noticed that sometimes my generals lose stars although their army stays put in the province and does no fighting for a longish time. Moreover, sometimes when a general (with his army) is moved to an enemy's province the number of stars is reduced, but when he is replaced to his former position he retrieves the lost star(s). What are the reasons and how it can be avoided?

Check the general's vices and virtues. Some generals have "skilled attacker" or "skilled defender" which means they only get command star bonuses when attacking or defending.

Generals can also permanently gain/lose command stars due to other vices/virtues.

2. This can be exemplified by the following. Once I had a defence battle (expert, no modes) by a Catholic army (Aragonese, but I may be wrong) against the Byzantine. They had a couple of Kataphrakts, a couple of Byzantine infantry and other units - spearmen and other rubbish. My army was much more balanced with heaps of archers/arbalesters, solid spear units, mounted missiled units (Pharis or others) and some good cavalry. Moreover, had a pretty good number of reinforcements. I deployed them on a slight knoll and they had to advance across half the map to reach my positions through arid terrain. But after the first impact and a bit of melee my army routed and I couldn't rally it. The same with reinforcements. I can't explain it by valor differences since my general had 6 stars while the enemy's - 8. So, most of my units had valor 3 which could not have been that disastrous against their 4 considering the quality of their units. My general couldn't have picked up a good runner vice (at least I think so) as his previous performances were quite satisfactory (where do you think he got his six stars anyway). This kind of trouble I have from time to time. So again the question arises: what are the reasons and what could be done about it?

There are a few possible causes - a vice such as "good runner" seems the most likely - or that your units were too heavily armoured and got tired - or they were too far away from the general. Valour is not morale and the valour bonus from the general's command stars does not bestow morale on a unit as normal base valour does. Instead the general gives a morale bonus to his units based on proximity. Check the numerology thread I linked you to in the other post for more details on this.