I love the sternness of his expression, and there's clearly some intellectual/artistic arrogance going on! And I adore what he's wearing in the picture where he's playing his harp. I hope you draw more of him!
Just like you got my headcannon Celegorm down, you got my headcannon Maglor almost perfect. Not quite as beautiful as his brothers, but kind of brooding, with an artist's muse. Love the top left, brow heavy gaze he's giving.
I kind of imagine the feeling from the top left picture like "I'm gettin' real tired of your shit, Fingolfin/Maedhros/Uldor/all the rest of my brothers."
Bottom left is him gazing up at his father as he starts to swear the oath. Kind of confused, but also really getting it.
Middle is him figuring out the best ways to sack Menegroth.
And the right-most picture is him composing the Nolodante, utterly repentant of all that he's done.