From information in Observer effect there was a potential Hell of a backstory for Hoshi.
A Gambler, Black belt, good with one of the older style Phaser pistols.
All things that a female gambler would need. Especially is she sat in on a game where there was a sore loser who would look for an easy taget and pick a female. Hoshi would need to be able to defend herself.
Actuallly, she sounded like she could have been a sort of buccaneer.
I like the image of a slightly dangerous, Gambling Hoshi. Rather than the timid Hoshi we got in the series.
I had a HUGE issue with the "I had a black belt" revelation. Nothing
in her behavior over nearly 4 seasons ever suggested she knew how to take care of herself.
I do agree if that backstory had been there from day one, that would have been so very cool. And what a great match she'd have been for Malcolm (yup, I'm a Reed/Sato 'shipper!)