It really was an understandable mistake. Anastasia thought that with her winsome charm and her bubbly spirit, she could win over any gay, brawny man. After all, she had Joachim eating out of her hand by the end of the game. Sure, she could fight Dart, but she wanted to go shopping after the matches, and Dart seemed like the perfect person to carry her bags.
Sadly, no one thought to tell her that pirates and gay aren't 100% synonomous. Well, Dart's axe told her, but that wasn't really all that helpful in retrospect. After the match, Anastasia decided to dedicate her time to trying to destroy all pirates while Dart finally decided that maybe he should get some new clothes so he didn't keep getting mistaken for a Village Person.