Dynasty Warriors: Strikeforce

It would be nice to get a little more details, I'm finding this to be VERY hard. I beat all three of the bosses and they came back to life and killed me.

All 3 of them are staff users, so bows would be super effective, and it's much easier to hit them with a bow than a melee weapon (as an aside, your 2 weapons should be one melee weapon and a bow in my opinion). You only need to defeat Zhang Jiao both times, his 2 brothers don't matter.

If you are still having trouble you could do the typical RPG thing and level up more, or create a better bow at the blacksmith. Salvo is a useful chi for a bow user, but I'm not sure if it's available in chapter 1.

Make sure you go into the stage with a bunch of the best meat buns and whatever it is that increases focus (don't remember) so you can stay in fury constantly.

Failing all that, you can change the difficulty to easy, though you get less experience that way.