Your costume suggestion
As a man of only one arm and one leg, you like to keep things simple so black trousers, black shirt and black cloak make up your signature look. Black helmet is intimidating but optional.
You are a tender soul, who uses bluster to hide a difficult childhood. Bullied terribly by the little girl next door, you eventually found your way to be apprenticed with the clumsy but kind Grey Knight. When the Grey Knight died not long after, you inherited his armour, painted it the colour of your nightmares and journeyed back to chop off the head of the girl who teased you. Instead, you ended up marrying her - until she left you for a sword merchant three years later.
INTRODUCE YOURSELF AT THE START OF THE GAME BY READING THIS
I am he who guards the way. In the far north, they call me The Shadow That Bleeds in the Night-Time (And Also Often the Day-Time). In the south, they do not call me very often. But here in the middle, here they call me The Black Knight. The King asked for me by name after hearing of my sacrifices and bravery in battle. If he’d sent for me sooner, he would still be alive. Nobody would have got past me. I move for no man. I sometimes give way to women.