There are items called "Start SPD, DEF, ATK, MAG, etc." they buff you right at the beginning of battle.
You can upgrade them in the armory with scrap metal up to level 5, but I don't know what that does.
I might be wrong, but when Assassins throw their panic bombs at me, I'm unable to do ANY damage to them, we're the only two nearby and my flamethrower is locked right on him, but no damage at all! If that is how it really works I think invincibility in an area is overpowered.
These may indeed be added in a future polishing update !!