This is now even a queston

Marguiet took out a whole reaper with a piece of scrap metal, ryley has to have a high-tech knife and a freezing gun or just a whole ass mech suit to even attempt to beat one

I feel like margareit would win since she's an experienced mercenary who is trained extensively in survival and especially combat. Ryley, although pretty tough, is canonically a non-essential systems maintenance chief on the alterra.

This is literalyl a slaughter @LoneSurvivr , ryley is hot garbage compared to marguiet.

Ok, I know Marguerit is a trained mercenary and MDF/TSF veteran, Can we take a moment to realize that Ryley Robinson can open a 12,041 pound hatch? Think about this, if you build a compartment at the negative build limit, 8,194 meters below sea level, the hatch would "weigh" about 12,041.6 pounds, and Ryley is able to open it near effortlessly. Also, Marguerit was worried about exhaustion before the Reaper's corpse floated to the surface meanwhile this glorified Alterran janitor can swim for infinite distances. I think Ryley could kill Marguerit with a Stasis Rifle and a "fairly reasonable" amount of Gas Pods.