Yes, it's an arm, and it's attached to someone who is very unhappy. Greta releases him as if he's burned her and scrambles back a yard or so, though not before she's brought them both crashing to the ground. At least they're still atop the cliff, which is better than the alternative.

"I--I beg your pardon," she gasps out, lifting a hand, palm out and placating. "I, er… it was an accident." Well, sort of. She definitely meant to grab something, just not an angry man.

The ground quakes again, and Greta moves away from the cliff's edge before she risks getting back to her feet. "We should leave this place," she says with a shaky nod that conveys both apology and a potential farewell (because she has enough to do without getting mixed up with yet another strange man, and this one distinctly un-charming, and there's no rule saying they need to flee in the same direction). "The giant," she adds, on the off chance he's not aware that that is the threat they're facing.