"The deciding factor between the two was their fighting skills!" Keon answered his own question as he sees how the Lords were confused and doesn't know the answer
The answer might be pretty obvious but that is only for normal people. The Lords' battle senses have dulled by a lot already
The longer they were in their current rank, the more their senses dulled
Lords focused on reaching higher heights. Those that don't have any Supreme Domain would spend all their time condensing one
As for those that already have a Supreme Domain, they would spend their time condensing another one
But of course, even if a Lord was given a lot of time, they might still not be able to condense a Supreme Domain since they were simply lacking in talent
As for condensing two types of Supreme Domains, that is an even harder thing to do. The Overlord's Vassals don't even have one Lord that has two Supreme Domains