The link appears to be broken. Mostly just wanted to see what it was and let someone else use the code or whatever (unless money mmmm), but I guess it doesn't matter.
It's a gender specific noun. The -tress ending to a word indicates that it is a female who does something. So a "swordstress" is a woman who uses a sword. It's not actually a real dictionary word, but native speakers understand it. The real dictionary word to use would be "swordswoman" or "sword mistress", but those don't sound as cool.
The male equivalent word ending would be "-er" or "-or", but "swordster" isn't really a word either. More clear cut examples are things like "waiter" and "waitress", "actor" and "actress", "master" and "mistress", etc.
Thanks for the explanation of rules, I do realise that and understood what the word means once I saw it. My previous comment seems to do a poor job of conveying the thought. :) It's not that I can't understand what "Swordstress" means, it just sounds (looks, whatever) weird to me. I suppose that's my problem and a direct cause of not being American (i.e. a native speaker). She looks nice anyway, even though I'm not a fan of that much girlishness (I can into coining words too! xD). Tl;dr: no offence meant, I'm just your average crazy being of teh interwebs.