He didn't say much; in fact, the Garner is much heavier than that heavy machine gun, yet he can still swing it with great force, let alone his little lion.
Moreover, if it weren't for the cannons and shells being too large to carry and lacking structures for a single operator, even if they brought a tank's main cannon, as long as it doesn't exceed two tons, Olivia could carry it around... at least she could before. Her current state is not optimal, and her strength may be greatly diminished, but operating a standard machine cannon is still no problem.
Sasha was truly stunned by Leon's words. She momentarily lost focus, furrowed her brow, and tried hard to imagine the sight of a person firing a machine cannon. She couldn't help but support her forehead, trying to remain calm, "Alright, I'll try to find you both some large-caliber anti-armor weapons, but it will take some time. We need to modify and add handheld grips to aircraft weapons... Dawn be upon us."