As far as I can see, there's no possibility right now to show weakness of country otherwise than by looking at ruler. If he/she is strong, much more soldiers come from their vassals and demesne. If they're weak- less. But still, playing as Byzantium and having huge territory is enough to defeat most of rivals. That's not historically plausible. So here are few ideas for "tweaks", that would make game more satisfactory (so maintaining already conquered territories won't be addition to conquering new ones):
1. Legitimacy: It's barely annoyance in Europa Universalis but would fit perfectly here. Usurpers should start with lower legitimacy while legal rulers- with higher. On the other hand, if legal ruler was a tyrant and has been deposed, usurper will be probably well accepted. Low legitimacy means that pretty much anyone in country (but having "main" realm culture!) gets Claim on Throne CB. Of course, more legitimate usurpers will get it faster. But ruler having 100% legitimacy can't be deposed by anyone. Legitimacy also lowers revolt risk and is lowered by acting tyrannical or by weakening dynasty (bastards).
2. Different governments- yeah, I know it's pretty big thing, but right now there's no place for small countries. They're simply eaten in seconds. Piechengs for example- historically Byzantium barely beaten them. In CK2 they're punchbags disappearing few years after start date. In reality during war they had 80k soldiers! That's plenty isn't it? So nomads like Piechengs should have much soldiers- but they shouldn't be able to conquer anyone! In their case, they can only raid enemies, pillage provinces and so on. After some time, they can claim another province- when their population is big enough. At some point though, they'll have to create more centralized government- because such realm will be unstable and hard to maintain. It's just an example- other governments would be Despotic (Byzantium) and Muslim (Muslims
).
3. Country decay- it's somehow similar to Muslim decadence- but more interesting. Principle is the same- higher decay= more problems. Decay is gained (which is BAD) when weak ruler is on throne, new provinces are captured, ruler has been excommunicated or important territory has been lost (for example- Byzantium loses part of Greece). Bigger realm is, faster decay is gained. Decay is lost when ruler is good (better ruler- faster lowering), core territory (same culture) has been reconquered, country decentralized (higher centralization- faster decay). High decay means that armies have low morale, tax rate is lowered, less soldiers come from demesne and vassals. It's very important thing- that means, that capturing everything is no more a good idea.
4. Dividing vassal opinions about ruler and revolt risk- with newly introduced faction system, many realms became war zones. Sometimes Europe looks like mosaic of counties without any central power. It's not historically plausible and no fun. Fixing it should be easy- this idea combined with decay should do well. Rulers traits no longer decides that everyone in realm revolts- ruler can be unpopular, but as long as he doesn't take any action against his vassals, he should be safe (of course some decisions and events making antagonizing vassals tempting should be introduced). In 1.06b Byzantium held well, because weak rulers were deposed very fast and good rulers came. Thus Byzantium blobbed because it already was one of the strongest countries. This idea will prevent this- weak rulers will keep ruling. They'll be only unable to expand realm borders, usually even fighting for preserving them.
5. Government advance- Despotism was more efficient then Feudalism. It had its weaknesses though. Historically rulers tried to gain more power, while their vassals tried to prevent it. In CK2 we can pass laws that picture monarchs power. Highest level of feudalism should be low level of Despotism then. Ruler tries to play "Va Banque" (decision with requirement being on highest level of crown authority) and starts civil war. He loses- he's deposed. He wins- he's despotic (or rather absolute) ruler. Vassals get events- either they fight with king or they become governors (can be appointed by king). Levies become standing armies (less in numbers but more efficient- can be achieved by using retinues system). It'd be also great thing for Byzantium- and restored Roman Empire.
1. Legitimacy: It's barely annoyance in Europa Universalis but would fit perfectly here. Usurpers should start with lower legitimacy while legal rulers- with higher. On the other hand, if legal ruler was a tyrant and has been deposed, usurper will be probably well accepted. Low legitimacy means that pretty much anyone in country (but having "main" realm culture!) gets Claim on Throne CB. Of course, more legitimate usurpers will get it faster. But ruler having 100% legitimacy can't be deposed by anyone. Legitimacy also lowers revolt risk and is lowered by acting tyrannical or by weakening dynasty (bastards).
2. Different governments- yeah, I know it's pretty big thing, but right now there's no place for small countries. They're simply eaten in seconds. Piechengs for example- historically Byzantium barely beaten them. In CK2 they're punchbags disappearing few years after start date. In reality during war they had 80k soldiers! That's plenty isn't it? So nomads like Piechengs should have much soldiers- but they shouldn't be able to conquer anyone! In their case, they can only raid enemies, pillage provinces and so on. After some time, they can claim another province- when their population is big enough. At some point though, they'll have to create more centralized government- because such realm will be unstable and hard to maintain. It's just an example- other governments would be Despotic (Byzantium) and Muslim (Muslims
3. Country decay- it's somehow similar to Muslim decadence- but more interesting. Principle is the same- higher decay= more problems. Decay is gained (which is BAD) when weak ruler is on throne, new provinces are captured, ruler has been excommunicated or important territory has been lost (for example- Byzantium loses part of Greece). Bigger realm is, faster decay is gained. Decay is lost when ruler is good (better ruler- faster lowering), core territory (same culture) has been reconquered, country decentralized (higher centralization- faster decay). High decay means that armies have low morale, tax rate is lowered, less soldiers come from demesne and vassals. It's very important thing- that means, that capturing everything is no more a good idea.
4. Dividing vassal opinions about ruler and revolt risk- with newly introduced faction system, many realms became war zones. Sometimes Europe looks like mosaic of counties without any central power. It's not historically plausible and no fun. Fixing it should be easy- this idea combined with decay should do well. Rulers traits no longer decides that everyone in realm revolts- ruler can be unpopular, but as long as he doesn't take any action against his vassals, he should be safe (of course some decisions and events making antagonizing vassals tempting should be introduced). In 1.06b Byzantium held well, because weak rulers were deposed very fast and good rulers came. Thus Byzantium blobbed because it already was one of the strongest countries. This idea will prevent this- weak rulers will keep ruling. They'll be only unable to expand realm borders, usually even fighting for preserving them.
5. Government advance- Despotism was more efficient then Feudalism. It had its weaknesses though. Historically rulers tried to gain more power, while their vassals tried to prevent it. In CK2 we can pass laws that picture monarchs power. Highest level of feudalism should be low level of Despotism then. Ruler tries to play "Va Banque" (decision with requirement being on highest level of crown authority) and starts civil war. He loses- he's deposed. He wins- he's despotic (or rather absolute) ruler. Vassals get events- either they fight with king or they become governors (can be appointed by king). Levies become standing armies (less in numbers but more efficient- can be achieved by using retinues system). It'd be also great thing for Byzantium- and restored Roman Empire.