I've figured out why I think it's attractive. Girls with SKILLS (bo staff, nunchuks, etc) are attractive to me.
I've known so many women who were only interested in social bullshit, clothes, etc. that when it seems like a girl actually has an interest that doesn't involve other people, shopping, clothes, a TV show, etc. it's appealing to me. I think the same goes for alot of guys.
When you see a girl who knows how to do some shit or has a genuine interest or ability it's a plus imo.