Uhhh... why?
No. Seriously. WHY?
I am a firm believer in the conservation of plot. Never add anything that doesn't serve the plot, and perferably, serves it in multiple ways.
Example: I created a magic system. The magic system DIRECTLY affects the player's options in dealing with problems. For example, why is it that everyone else dies horribly when trying to absorb a demonic mana core when the Antagonist survives.
"He's special"
Well, yes, but WHY is he special? I worked out the unique set of coincidences that must happen for someone to survive, because after he survives, he tries to grant the same power to his one true love and winds up killing her. Thus, Tragic Villain.
You want a unique way of explaining the various levels of "jobs". WHY? What does this serve other than to make more homework for the reader? HOW will this change your world? WHY have a rarity index at all? Is it "in universe" and universal? Or is it an "In character" way of sub dividing the jobs?
Look at d20 3.0/3.5
To the player, each and every class is available, but IN GAME, there are only three "tiers" NPC, Base, Prestige. Mechanically speaking, these are all different types of classes. However, all classes are not created equal. Here. A quote from my Noob Handbook.
The Tier System
We’ll go into detail on classes later, but let me mention the tier system. The tier system is both brilliant and idiotic. It is a system for breaking down the classes and rating them in tiers as to which one is more powerful (one is best, six is worst) all other things being equal.
That last part is the important part. For you, the player, it’s useful. For comparing different players to each other, it’s useless. The tier system puts wizards at one and monk at five. Yet, in the campaign I am running, the monk PC is the scariest thing I’ve ever seen. By the rules, I cannot kill her and she mops the floor with everyone. I’ve mind controlled the whole party and turned them against her and she not only won, but took them all alive. I’ve cheated and broke the rules and made monsters ten challenge ratings higher then her and in personal combat she mangles my worst monstrosities. I have literally stripped her of all equipment, dropped her in an alien dimension where reality does not work as intended, and nullified all magic. She never broke a sweat.
Now, when she was playing a wizard, it was ten times worse.
Some players have a gift. A knack for the game. She’s an accountant in real life and worked dealing with state and federal regulations and had to stare down the ATF more than once. She won each and every time. (She does my taxes, btw.) Some people are deadly with a spreadsheet and she’s one of them. I don’t care what class or race you give her, she’s going to optimize it in ways that will make you gape and then…
She’ll get bored. Once she’s used a trick or combo, she’s done. It’s lost its luster. That’s what makes her so nasty. She never looks back. Never does the same thing twice. Once she comes up with something, I can prepare against it, but she never uses it again. We joke she’s kind of like Doctor Who. Unarmed, outgunned, outmatched, you still know the bad guys are going to lose. It’s not in the script, it’s just what she does.
This might be you. You might never reach this level of nerdvana. My point is, the tier system is only good at comparing the classes to each other. The mistake people make is to compare them across players. I’ll put my group of five players up against any other group of eight on the planet because my players are a lean, mean, optimized dungeon crawling machine.
What’s this got to do with the tier system? People are going to try to tell you to play X or be a Y because someone else told them that this was the way to play. Sometimes not knowing something won’t work is good, because you don’t know you can fail. It isn’t all about the best PC, because if it was, everyone would play Pun-Pun and be done with it. It’s a balance between teamwork, power level, optimization, and style. I got one player who couldn’t optimize his way out of a paper bag, but nobody makes the group fall down laughing more than he does. He also has the record for most resurrections with the same PC. So go look at the Tier System thread sometime, but take it with a grain of salt.
So First question to ask yourself:
WHY DOES THIS RANKING SYSTEM EVEN EXIST?
What does it factor in? (teamwork, power level, optimization, and style)
What purpose does it serve the STORY?
Are you doing a story like "Heavy Knight" where the Isekai'd MC knows that Heavy Knight class is a broken monstrosity that absolutely bodies everyone else but when he winds up "In Universe", everyone thinks Heavy Knight is F-tier?
If so, why do you want to confuse the reader by calling it "Bob-Tier"?
Look, you want a unique system? Then that's simple:
Name every "tier" after a person.
Sir Drecken Bridge was the first S-Tier, so they call it Bridge Tier.
Prince Randolf died in a duel so infamous, with a loss so complete and embarassing, they call "F-tier" Randolf-tier.
And so on, and so on. Then at least there is some LORE to the changes, but in the end, what you are making is HOMEWORK for the reader. Changes for the sake of change just to "not be like everyone else" is usually a waste of time.
I do use different "tier systems" myself, but it's DCBAS or FDCBA or Epsilon, Delta, Gamma, Beta, Alpha. Why? Because have have multiple different worlds that interact and each one would be slightly different, but not so different as to be completely alien to the reader. When you are the super hero setting, it's greek. In the one with Japanese overtones, its DCBAS, in the "Western ambiance" setting, it's FDCBA and
never S, but they do use Minus and Plus signs, so you can be A- or C+. This is a subtle reflection of the culture and source of the "memetic contamination", which is a whole other conversation.
The point is, the different tier lists I use have a POINT and are plot related. The clever reader will know what is going on if a character in one setting says, "Beta tier" if normally its a japanese style tier system.
So, I repeat myself:
WHY?
