SUGGESTION- Please read!

[Chenier]

So, the idea is to sell a prisoner to another realm only if executing such noble is already an option in the realm that captured it.  Right?

The restriction I deem most appropriate would be the inability to transfer a noble to a realm where he was banned if you have not banned him yourself.

If haven't banned him, and you ship him to a realm where he wasn't banned from either, sending him there does not increase his threat of death. As such, I don't see any issue with this possibility.

[Sacha]

Might that not lead to nobles being banned for the purpose of being handed over the next time he's caught?

Now that I type it, not sure if that would be bad or not...

[Chenier]

Might that not lead to nobles being banned for the purpose of being handed over the next time he's caught?

Now that I type it, not sure if that would be bad or not...

When do judges, when given the possibility to banish the enemy, chose not to? Never, unless there's some kind of prisoner agreements. And those usually regulate more what happens after the banned state, not preventing it. I don't think this feature would alter that behavior.

[Sacha]

Well, I temporarily forgot judges can only ban people caught red-handed... so that fixes that.

[Eldargard]

Yep.