Oh, I Think His Power Was Demonstrated Sufficiently. He Understood Perfectly Well That The Orcs Were

Oh, I think his power was demonstrated sufficiently. He understood perfectly well that the orcs were starting to stop loving him, to stop believing in him. And he did nothing about it because he knew it was necessary. Some of them had to die so that many more generations after them would not fall under Sauron's power. He was not only willing to sacrifice his own children but was also ready to perish at their hands to ultimately stand up for their future, even at the cost of his own life. In my opinion, that is an incredible strength.

Honestly, I haven't seen such a terrible story as Adar's in a long time. Not in the sense that it is poorly written, but in the sense that his storyline and his entire life are absolutely hopeless. His life was spent in suffering alongside Morgoth and Sauron; he witnessed how they killed and tormented his children, he was tortured too. For a brief moment, they freed themselves from Sauron's power, and Adar did everything to ensure that Uruks did not fall under his control again. He was ready to turn them against him, to feel their distance and their waning love for him, he was prepared for them to kill him, just so they wouldn’t become slaves again.

He dies right after realizing that the ring could heal him, after a new path opened up for him in alliance with Galadriel. Sauron looks at him and Adar understands that Sauron has won, and that everything that came before was in vain.

This is an absolute, total nightmare and shattering of all hopes.