I don't know if I'd still consider these weights to be accurate. Probably not? I dunno. I'm not sure where I got 120 or 137 from. I honestly don't know if those are appropriate given her height and build, but whatever. It's trivia that doesn't really matter short of an exciting storyline involving some sort of limited weight capacity with something.
Anyway, Greg can totally sense stuff. Unlike Elliot, Greg's ability to sense power and danger is meant to be somewhat consistent and as inconvenient to plot as it feels like being.
So how powerful is Greg? I'm not sure how to quantify it, but he IS the instructor at an anime martial arts school. This basically implies that he's the most badass guy around until there's some storyline in which he declares someone else to be of greater power, or until there's some villain he needs to describe as "too strong, even for me".
Commentary added October 15, 2014