[the phantom]

I don't think Feanor particularly lacked self-control, I just think he was very resolute, didn't want to be anyone's b!%ch, didn't like his father getting killed, and didn't like his creations (which were beyond the reach of the Maia, probably even some of the Ainu) getting stolen by the same guy that corrupted him and killed his father!!!
Put yourself in his shoes. I think you would've gone on a mad revenge quest too. It was all about getting to Melkor. First, the Valar let the evil little rat run around free, secondly, he had robbed Feanor of his greatest treasures, Finwe (his father) and the Silmarils (the greatest things ever made with hands), and lastly, the Valar weren't going after Melkor to take him out. If I was Feanor I would've taken off after him too, and I would've been pretty ticked off if people had said that my actions were whiny, emotional, and impure after all I had been through.
He held a whole multitude of people to his will and even told off a herald of the Valar (who bowed to Feanor after Feanor spoke). He fought all alone at the front of the battlefield, surrounded by balrogs, and never retreated until he was struck down. Doesn't sound weak to me. An emotional weakling would've been cowed by the thought of going out away from protection and trying to take on an unbeatable enemy.
I think he did pretty well considering the most powerful being on earth, Melkor, was trying to destroy and corrupt him.
Feanor had the right idea with not practicing self-control. It wasn't the time for it, it was the time to overthrow Melkor. If the Valar had just gone with Feanor to overthrow Melkor, it wouldn't have been nearly as tough as it was later when they finally got our of their rocking chairs and did it. Feanor was trying to do what he knew had to be done, and wasn't gonna let the Valar or other elves stop him. It's not always time for self control!

(I apologize if I'm coming on too strong, but I'm very passionate about this topic. Since the first time I read Silmarilian, I've sympathized with Feanor, and admired his fire and resolute actions, and I think he did better than any of us would've done in his situation, unless you think it would've been better to sit in Valinor and cry while Melkor takes over the world.)