These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Game Breaker - Eddie's Overdrive and Combo Attack skills are gained near the very beginning, and can annihilate bosses in just a few rounds even quite a ways into the game. By the time it stops being as effective on bosses, you've gained your plot-unlocked ultimate attacks.