In the end, humans are the ones doing most harm, also, why the dwarfs didn't try to sell other stuff besides swords ? like cooking pots, or sledge hammers, nails, saws, construction stuff, what kind of economy they have ? depending of another country to get income.
Same for the elves selling medicines, they can still do the same, selling medicines, but not only for soldiers, but for civilians too, even common medicines can do some difference, like pain-killers for headache orbellyache medicine.
I noticed that the dwarfs have problems with food production, hunting its not reliable most of the times, they can try to raise domestic animals for food, or make a few farms too.
Elves and dwarfs blaming humans for their problems kind bothers me, the only one to blame about those problems is themselves, if they don't invest in agriculture, how do they expect to have enough food, same for elves, if they don't invest in another in their own market, how do they expect to get any income ?
I know this kind of manga isn't focused on such kind of matters, but its kind hard to ignore, but if was to actually adress huge problems, would be rather easy to point out the lack of security of the demon lord castle, or the others always trying to capture the priestess instead of just killing her already.
quick note, might had some grammar errors, english isn't my main languague, so, sorry about any grammar mistakes.