@zivoy
If I were to wager a guess, it would be "monster experience". Soliders are trained daily, to be sure, but only against other soldiers- usually. Where a mercenary/adventurer fights against both man and beast.
It may also be equipment typing. The armor of the soldiers here looks almost mass produced. Probably because they're mob/throw-aways, but still worth looking at. Armor to handle another human's strength, not something literally named "Grinder".
Also, if I recall, they're group is high-end. Maybe even akin to a Hero Party. And, to add, the spiteful knight was recently disgraced and likely demoted. Given weaker or subpar soldiers to command.
This is all opinion, though. So form your own headcanon.