Considering that rage lets you actually FLY, I'd say it's very, very supernatural. That's the hillarious thing. The notion that a fighter could swing his weapon so hard that he flies is absolutely impossible. But, my guy getting so angry he can literally fly in to a rage (heh) is no problem whatsoever.
But, I mentioned this earlier about what if you had a caster with a list of 20 spells total for their spells, same as a Battlemaster has only 20 maneuvers. Let's split that up over 9 levels:
1st (4 spells) - Expeditious Retreat, Jump, Shield, Thunderwave
2nd (4 spells) - Alter Self, Invisibility, Knock, Scorching Ray
3rd (3 spells) - Fear, Fly, Fireball
4th (3 spells) - Charm Monster, Stoneskin, Ice Storm
5th (2 spells) - Cloudkill, Telekinesis
6th-9th, 1 spell/level. - Circle of Death, Plane Shift, Earthquake, Meteor Storm
((Note, taken from the 2024 Sorcerer spell list))
Now, there's the benchmarks. That's what a fighter should be able to do, without magic, although a supernatural or whatever you want to call it source is fine. No actual spells. Just using his weapon/spirit/whatever, the fighter or rogue can duplicate THOSE effects. So, instead of needing to be 14th level to fly, our fighter can do it at 5th. Our fighter can slam the ground so hard to cause earthquakes at 15th. So on and so forth.
If we're going to get class parity, this is what needs to happen. Or, we need to drastically reduce what a caster can do. Either way.
considering martials tend to lean more into passive/resourceless boons here's how i might equate some of those to what a fighter might get,
1st (4 spells) - Expeditious Retreat,
Quick Step(passive) - base movespeed +10ft
Athletic(passive) - double your height and distance when calculating jumping, gain a climb and swim speed equal to half your walkspeed
Defence(ability) - use your BA to defend, increasing your AC equal to your PB to the start of your next turn
Clear Some Space(ability) - all adjacent creatures make a STR saving throw to resist being pushed 10ft away(no damage),
2nd (4 spells) - Alter Self,
Rank and File(passive) - you have advantage to gain information from or pass yourself off as part of other groups of guards or knights, or as a noble while wearing noble's clothes
Greased and Padded(passive/toggleable) - remove any disadvantage on stealth your armour applies or gain advantage if it does not, your movespeed is halved while doing this, note, this is not cancelling out your disadvantage but removing it and therefore means you can gain advantage.
Bend Bars, Break Barrels(passive) - you have advantage on checks to destroy or manipulate your environment by force
Burning Blade(ability) - you ignite your weapon and the next PB times you hit your target catches on fire, your attacks deal fire damage until this effect ends, struck targets take 1d6 fire damage at the end of their turn per hit until they or an ally use their action to remove one stack of ongoing fire
Fearsome Weaponry(ability) - make an intimidation check to inflict Fear condition on PB enemies within 30ft who can perceive you, roll weapon damage+MOD, you can distribute the resulting damage as additional modifiers between your intimidation checks
Hang Time(passive) - when you take the jump action you can choose to gain an additional turn of airborne movement before you land at the end of your next turn, you cannot change the direction you were travelling in unless you collide with a solid object such as a wall or flying enemy, if you were affected by the jump spell increase the duration to two turns.
Blitz Attack(ability) - take a full attack action against every enemy within a 10ft radius of you
4th (3 spells) - Charm Monster,
Biggest Threat(ability) - after you manage to hit a creature you can force them to focus on you, they have disadvantage on attacks made against other creatures, at the end of their turn they can make a WIS save to end this effect, if they succeed they are immune for 1d4 rounds.
Master Defense(passive) - while not wearing armour you have a passive AC of 11+CON or DEX, while wearing armour you gain an additional +2 AC from it, shields provide an additional +1.
Reaching Control(passive) - enemies within a 10ft radius of you must move as if in difficult terrain otherwise you get to make an opportunity attack as a free action.
The following spells i didn't think were especially good picks to equate to abilities a fighter might get so i've swapped them out for others of the same levels i think might fit better
5th (2 spells) - Cloudkill, Hold Monster
By the Scruff(passive) - you have advantage on checks to grapple a creature or to maintain a grapple, you may grapple creatures up to two sizes larger than you, your movement speed is not reduced unless you are dragging a creature two sizes larger than yourself, you have advantage on intimidation checks to creatures you have grappled.
Telekinesis, Skill empowerment
Master Combatant(passive) - you gain an additional bonus to your to-hit equal to 1/2 PB on all your attacks, alternately you can gain your full PB to a single attack that turn
6th-9th, 1 spell/level. - Circle of Death, Move Earth
Shape Landscape(ability) - this is mostly the same as Move Earth, but takes an hour and can affect constructed stone (though it is turned to rubble in the process)
Fearsome Presence(ability) - all enemies in a 25ft cube either centred on you (as of using the ability) or up to 25ft away are considered restrained until the end of your next turn.
Earthquake, Antimagic Field
Arcane Resistance - you gain magical resistance, spells and magical effects have disadvantage against you/you have advantage to save, magical effects do not impede your movement.
Greater Surge(ability-reaction) - you can trigger this ability whenever a creture ends a turn, you can take a full turn's worth of actions.