I'd argue that this is not so important as putting up a good fight when the occasion calls for it. After all, if a protagonist's primary method is good old fashioned melee, making the villain a mage immune to melee is cheap rather than threatening. If the villain is able to match the protagonist in his chosen method of problem elimination, that's better.
Yeah, or show capable of personal traits and qualities worthy of admiration.
Guy ain't an antagonist just because you fight him most of the time.
I was alluding to someone like Gaunter O'Dimm who completely outmatches Geralt.
You don't murder him because of some man child's temper tantrum. He deserves death for his incompetence, the worst crime of all.
Incompetence implies faulty reasoning. His reasoning was sound given what he knew. If you want to blame anyone, blame the Wardens for underselling themselves by keeping things secret even from Cailan (and implicitly Loghain) just because the king was an incompetent buffoon who took fairy tales for granted. As far as the blame game goes, Cailan > Wardens > Loghain.
His reasoning is of little importance. The failure at achieving his goals is what matters and playing blame games does not change the results. He called the shots and his shots misfired, that's on him. His failure at judging/acquiring information is no excuse. Lets take a look at his other great efforts. He tries to take out a political enemy by poisoning and fails. He tries to assassinate you and fails. He tries to unify Ferelden under him but causes a civil war and he is unable to stop the dark spawn threat thanks to that. The arguments for calling him competent are more than thin when he fails for the largest part at the tasks that he sets out to do. His value as asset is also low since you have to swap him, which leaves you pretty much as well of as before. Leaving the facts aside that he wanted to assassinate you and has proven himself to be a traitor at the very beginning. Not exactly the person that I would want to have my back.
Then we're not talking about competence. He made the right choice at Ostagar with the information he had available while Cailan did not. The fact that the rational decision which Loghain had taken was not - with hindsight - a good decision doesn't speak of the man's incompetence, but simply of bad luck given that his decision was intellectually sound in the circumstances in which it was taken. The good outcome that would have ensured were he to have sided with Cailan would've instead made him a lucky, yet incompetent strategist since such a choice would've been rooted either in blind obedience to an incompetent king (which would've made him a traitor to Ferelden to which his foremost loyalty lies) or to the same sort of overvaluing of the Grey Wardens that Cailan did. And he could not have known more about the Grey Wardens since Cailan gave them a pass simply because he was vainglorious, not taking the Darkspawn threat seriously and caring more about the legend of the Wardens rather than their actual capabilities. You can't blame a man for not having more information when gathering that information wasn't his job (nor was it possible to gather it when his superior cockblocked his efforts to further scrutinize the Wardens).
All of them due to the meddling of the player character. And the player character is pretty much a Mary Sue, something that we as gamers tend to overlook since it makes for a good hero's journey type of story despite the obscene amount of luck that the PC has throughout it in being the right man at the right place & time to fuck up Loghain's plans (among other things). Had the Warden been just another story NPC, he would've been either long dead or just faded into obscurity after Ostagar.
An experienced champion is objectively the better choice over an unexperienced (and undisciplined) templar. And since the PC proved his worth over him, that makes Loghain the most loyal companion given that he now acknowledges that the fate of Ferelden depends on your continued success as leader of the Grey Wardens.
Which is a fair stance to take if you put loyalty to the monarch above the wellbeing of the country. Loghain did not.
L'État, c'est moi
Some nobles rose in rebellion.* And they would've been irrelevant were it not for the PC (see also how it is the PC's swaying of even more nobles to his side that decides the fate of the Landsmeet, not to mention that even the Landsmeet itself is a consequence of the PC's saving of Eamon).
I'm quite sure those nobles had many people fighting for them.
