Shield Based Ability Class??

[SpicyBoi_Nezu]

So I have already fallen in love with the new anime "The Rising of the Shield Hero" and I was wondering if anybody has seen a Homebrew class in any edition of D&D that is anywhere near that style. Mostly because I love the concept of essentially a spell-caster class, except it is exclusively based on "Skills/Abilities" gained by defeating monsters and "feeding" them to the shield. As explained by the show, he has obtained so many skills that he has lost track, and yet by looking at his "Stat" list, his (what I assume to be) Attack, Accuracy, and Speed have not changed, even though he is level 16 at the start of the episode. I believe that this class would consist of almost exclusively special abilities, and would work similar to a spellcasting class, where at each level, you gain an access to higher level abilities, and there is a large list (think Wizard/Sorcerer spell list in the spell compendium), but the only difference would be, and I'm making an assumption here, the Shield Hero would not be limited by daily use abilities, closer to essentially cool-downs (Higher Level Abilities can take between 4-5 rounds to 5-6 Hours before you can use them again). Also something that I believe would be cool would be if there was a skill tree (Think Wizard Spell Schools or Cleric Domains), where to gain access to that tree, you have to meet certain requirements, like feeding a certain type of fire monster to the shield so you can gain the fire shield tree, or feeding other sets of armor or weapons to the shield to gain more offensive or defensive skills, and you can "Level Up" those skills by adding more and higher level versions (See Lesser, Greater, Minor, Major, & Mass versions of spells) to your repertoire each level (Like A Spell-caster Does). And, like a spellcasting class, each level you would gain more abilities, as well as access to higher level abilities (Assuming you meet the requirements). Applying the requirements provides for even more diverse PCs where each character could be from a completely different area, with completely different monsters/plants, and have zero similarities with one from a different area. All because they are defined by what they're exposed to, a player in a water-based campaign or background probably would never acquire any fire-based skills, or one who has spent the majority of their time away from combat wouldn't have many skills applicable to battle, while one who has spent their entire lives in nature may have a large variety of plant, animal, and generally nature based abilities. Some may specialize in buffing teammates, another may specialize in out-of-combat skills, one might specialize in more offense based combat skills, and there could be a character based exclusively on Defensive skills, buffing their HP and AC, and reducing there effective offensive capabilities to zero.

All of these concepts are merely my interpretations of how I would do it, and I'm essentially asking y'all if you have seen anything similar, or at least for some recommendations on balancing my ideas. Also, feel free to add onto it, I'm open to ideas, because eventually I plan on making this class myself, and I want it to be as balanced as possible, while also still being fun.