I don't mean vicious like they're ripping off limbs and eating the stormtroopers or anything xD
I just mean to make them more dangerous and aggressive. Not just teddy bears jumping on top of the stormtroopers and killing them somehow. They have spears and arrows, for instance, yet we really only see ONE arrow do any damage.

The stormtroopers are too wussy because the Ewoks are too invincible and have no credibility as combatants. If we add some shots of Ewoks being fearsome, as well as Stormtroopers being more effective at dispatching them, both problems are fixed.