Hey, here’s the letter young Edward sends out in episode 3, in a desperate attempt to get his father to come home. Presumably he wrote it, given he put his name on it and everything. He’s got decent enough handwriting.
Here’s Ed writing a letter when he’s 12. (He even wears his gloves while writing which seems weird but whatever, maybe he hates looking at his automail.) He’s using his left hand and the writing is legible but completely different, way simpler with none of the letters joined up.
He’s visibly frustrated while trying to write with multiple failed attempts on the desk. I’m figuring it’s because he wants the letter to look nice with no mistakes and he’s having trouble using his left hand. Poor Ed!
The takeaway here is that the show is subtly conveying that Ed has difficulties with his automail and his non-dominant left hand. He can no longer write as he used to without his original right arm, forced to relearn how to write.
Zetalial 