Amy is a mercenary and a beserker, dressed as a maid.
It's not a fashion choice. Her mercenary partner, Dolf, asked her to wear it so that he can better disguise himself as a high class court magician. Amy hates the ploy but plays along since Dolf gets them great deals that Amy could never get.
She is usually quiet and timid. But when it comes to battles she is a formidable berserker. She wields two handed weapons like it's a children's toy and roars like a dragon. The face she makes alone can give her foes nightmares.