I would help you out but I play on the Xbox 360. Just try to beat it on Human (the easiest difficulty), buy as many Upgrades as you can to get stronger, buy a lot of the Health Cross, Devil Trigger Cross, and find all the Fragments to increase your meters. Use
this video to find all the secrets if you need help.
I've just completed "Vergil Must Die!" and "Hell and Hell" last night back-to-back. Even with Super Saiyan Vergil I still died a lot. Now I've officially completed every difficulty! I am done with this game forever!