That is a good point actually, but that's also...pretty damn stupid, I mean, stabbing the water stupid, for God's sake man, skill AND equipment matter.
But still, wouldn't the veterans at least have armour that resembled Lorica Hamata, anything better than the same football gear but with a couple of tire irons sticking out of it?
So why do they wear Pre-War football gear? It's clear that Lanius had his armour forged, so why can't the legion at least make some armour that would better suit legionaries