Aurora Borealis, The Art of War.
They are the second deadliest of the Arts, and they are the last surviving architect of the war's civilian militia. Now, they teach chemistry and kill war criminals in their spare time. Not bad for someone who is supposed to be blind.
During the war, Aurora was persecuted for being transgender (FtM), but managed to escape and lead a militia-operated armored cavalry during the Autumn counteroffensive. "Aurora" is not their real name, but an adopted name from the operation they spearheaded prior to their capture and escape, Operation Aurora Borealis. Aurora's true name is only known by a handful, but they are often referred to as Warmind Athena.
All characters in the anime,/manga refer to them as male *except* their best friend Arthur. This is an important plot point, and becomes a significant fact towards the end. Aurora never corrects Arthur throughout the entire story, though (which is also important), while correcting others who mistakenly refer to them as female at various times throughout the plots.