Not-heroic martial makes just getting killed four times in the row by something extra-killy rather possible, but yes it takes either massed infantry or heroic units and monsters to take Mathilde in straight combat now.
There are a couple of examples on the tabletop, tho. There is enough wonky cannon and fanon on the issue, I simply do not care about anyone's stance on the matter other than GMs, and fully expect their positions to vary from quest, leaning "no" in general.
More or less what I expected.