I haven't thought too much about what other upgrades Isabel might gain from joining the Swarm, but it'd be interesting to see those interact with what she's already got.
Battleroids are a concept from Bungie's Marathon Trilogy; they're described as cyborgs created from the reanimated dead, with heavy internal modifications. The idea that there were multiple generations is mine; the first were deployed at the asteroids Icarus and Thermopylae in 2194, with devastating results (this is the only battleroid incident mentioned in canon).
The second gen, made from living (and unwilling) subjects, were converted by MIDA to fight in the Third Martian Civil War (which began in 2442). Ten battleroids are mentioned as being smuggled onto the UESC Marathon
; in my AU-thing, these ten had received alien neural implants instead of MIDA's copies of said implants, and thus were the only ones who didn't go berserk. Isabel's one of these ten.
Her original upgrades include those implants, converted muscle and bone tissue, and various other technological doodads that are visible on her person (seen here
on fellow battleroid Vince, though note that only he has that extra port above the white thing on his neck). This translates to superhuman strength and endurance (the games lack fall damage, which is attributed in-story as a trait of the Security Officer's), potentially
the ability to affect the fabric of reality (it has to do with Marathon Infinity), and as far as my AU-thing goes, biological immortality.
The Marathon Story Page
has tons more info, if you're interested.