the answer... I could not find... no matter how hard I tried

catharsis - a purgation of the emotions

To gain a diviner, Grim Angels must willingly relinquish something. For Ein, it was his wings, for Malice, her future. For Ledah, what was lost was his ability to feel. Empathy, apathy, pity, comradery, hatred... everything. What was left was a tabula rasa, a Grim Angel that was a complete blank slate. That would do everything he was told, without his morality interfering. Without hesitation, questions, or doubts. Robotic, in a sense.

There seemed to be a disturbance in his placid exterior when Ein was taken away by Ursula and abandoned by Hector for dead. His face seemed almost pained at how disposable Ein's life was to Hector. Ledah had to have continued searching for him, which was against orders. If he had simply accepted Ein as dead, he would not have found him in Elendia, as Ledah had no business in Elendia. He was not ordered to retrieve Ein. Had it been Malice, she would have killed Ein for his treachery then and there. But Ledah simply questions him, asks him to return to his post, and goes. No matter how weak or helpless he felt Ein to be, something about Ein had to have effect Ledah.

So much so Ledah sacrifices his life, shielding the wingless young Grim Angel from a grizzly death blow. It seems that as he lay dying, and could no longer serve as a Grim Angel that whatever was done to take his emotions away was undone. It could be said that he knew, or at least suspected Hector of treachery the entire time, but as Ledah had no emotions, he could not be angry or offended. He seems touched that despite everything that happened between them, that Ein cared so much for him.

Ein's familiar, Rose, upon reflection questions whether Ledah had tears in his eyes at the end. He was free to cry, to feel, once more, even if it was only in death.