weapons are upgraded with crystal so start collecting early.
[Submitted by: Willey Maket ]
Earlier on in the game the enemies are somewhat easier to kill. When you kill the guys with pink crystal,it gives you points needed to upgrade your weapons so rather than avoid them, in areas where they keep spawning it might be a good idea to farm some crystals early in the game especially since you can find health/savepoints more readily earlier on and they dont fight back much. Kill them quickly so the multiplier goes up (I have the japanese version and I think the crystal multiplier works on how fast you kill? But it may be from combos. (I'm not sure because I can't read the manual or anything.) Also keep in mind as you progress you will get more weapons for each character which you might find to be more effective against groups of enemies or have higher attack damage than the weapons you start with so be sparing with your weapon upgrades early on AFAIK. There is no way to undo upgrades and take crystals back for new weapons you get. If I had known this when I started it would have helped me alot. I think it's all in the manual for you guys but good luck,this game can be frustratingly challenging so you want the best weapons/upgrades you can get. PS, so far I defeated almost any boss/sub bosses easily pretty much with the main heros second set of swords (rusty red colors) by holding block and pressing triangle for his spiral, drill looking, attack because it launches you past their guard while dealing minor damage.This usually gives you a chance to get a hit or two in from behind while they're stunned. It is also useful for escaping and attacking groups of enemies. Yes,I know im cheap but it works. Ideally try to find good combinations using more than one character for the win.

Completion bonuses
Complete the game on the Normal difficulty setting to unlock the "Movie Viewer" and "Sound Test" options under the "Extras" menu.

Quick knock down recovery
If you get knocked down, press X to get up. If timed correctly, just as you hit the ground, you will jump back up. If you do not time it correctly, press all buttons a few times to get up more quickly.