Does the power gamer play the same character over and over? Because there is a strongest build. If not... maybe there is other reasons they make a character.I am sorry but that just not always true. Some people DO in fact choose a class because it is mechanically good then come up with a story of an epic X to support it. You working on the assumption that all players are story player first, but while I see players that choose story and support with mechanics, I also see players who choose mechanics and support with story, On top of those I have also seen players pick a party job the support it with mechanics&story. None are wrong, they are just different types of play. We have 5 players in our group and all types are represented our group alone.
We have one "power gamer" who always try to be some awesome DPR build but does little to nothing out side of combat because he doesn't care, we have a player that wants a great story build but will not except anything with out some skill talent which makes them mechanically exceptional to support a "Justifiable arrogance" because he can support that arrogance in game by being actually good at something consistently, I picked a role (scout) then a less optimal class (because I like to go sub-optimal but make it still more than good because its the road less traveled and unique) the back it up with story, We have one player that's just says here is a class I have not played lets see how this goes, and we have a player that is all story based and did not care if the character worked mechanically or had a role he just wanted to be a "scoundrel rogue" and basically picked all stats and skills based on being smart and likable... more "Face" than actual rogue. The players who like combat but don't like story don't even use out of combat skill if they have them or want then, generally considering them class waste...
... And guess what... even with all these "cardinal sins" we play and have a great time with virtually no player problems. Most of the times when we have issues its between our story GM and player who actually know and care about the rules more than he does..... Still not really a big problem. Been playing for years and having fun.
So if Zardnaar want a mechanically stronger build as his priority. Their is nothing wrong with that. Its just his play style.
The PHB doesn't really have any good gish options IMHO. ... The Eldritch Knight takes a long time to come online/isn't that good and trips over its war mage ability at level 11 ...
So stripping out all of the class exclusive bits this is the basic half caster warrior template 5E uses.
But they do get iconic signature abilities: favoured enemy and lay on hands.Rangers , Paladins and fighters don't get too much at level 1. The combat casting thing can wait to level 2 or 3. Probably give it some cantrips lvl 1.
Basically don't want to design a dip class. As I said would rather have something functional than cute.
That’s a very tanky/ defensive power. Anything relegated to a role should probably be a subclass.Instead of smiting a magical aegis ability reducing damage could be a thing. The attack, hit cast spell thing might be better off on a subclass.
Instead of extra damage vs fiends and undead you get bonus reduction vs spells.
Looking at what I mused earlier and pulling from swordmage flavour, this class could be the guy in no armour or light armour that fights with a sword and magic but is protected by an inherent mage armour effect. Calling that "Aegis". That's a good solid level 1 feature as it sounds cool and invokes feelings of defence while also sounding arcane. IIRC the swordmage has a similarly named power.
Off the top of my head, I'd say that you can activate your aegis after a long rest through 1 minute of meditation, surrounding yourself with a light magical aura of protection that lasts for twelve hours. While your aegis is active, so long as you are wearing light armour or are unarmoured, you add your Proficiency bonus to your Armour Class.
And at higher levels, the Aegis could be augmented with other effects.
In addition to Aegis, the class maybe needs a small ribbon. Perhaps a couple small cantrips. Non-combat ones like prestidigitation. Make blade ward as well.
I still like the idea of the class imbuing their weapon (or shield) with magic. This might be a buff that lasts for 1 minute but recharges after a long rest. But you can burn a spell slot to activate it again, or augment the effect. Which allows it to scale nicely.
As this should balance with a 1st level spell (so a 1st level spell slot can recharge it), we can look at the wizard's Arcane Recovery as a guide for how many uses this should get. Which keeps the class in line with a multiclass fighter/wizard. Personally, I'd try and balance this class against a character using the build rotation of an eldritch knight fighter, wizard, fighter, fighter. So 1/4 wizard but 1/2 caster. That means the class might get a second free usage at level 14.
This would make the class look like:
[TABLE="width: 500"]
[TR]
[TD]Level[/TD]
[TD]PB[/TD]
[TD]Features[/TD]
[/TR]
[TR]
[TD]1[/TD]
[TD]+2[/TD]
[TD]Aegis, Cantrips[/TD]
[/TR]
[TR]
[TD]2[/TD]
[TD]+2[/TD]
[TD]Fighting Style, Imbue Magic (one use), Spellcasting[/TD]
[/TR]
[TR]
[TD]3[/TD]
[TD]+2[/TD]
[TD]Subclass[/TD]
[/TR]
[TR]
[TD]4[/TD]
[TD]+2[/TD]
[TD]ASI[/TD]
[/TR]
[TR]
[TD]5[/TD]
[TD]+3[/TD]
[TD]Extra attack[/TD]
[/TR]
[TR]
[TD]6[/TD]
[TD]+3[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]7[/TD]
[TD]+3[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]8[/TD]
[TD]+3[/TD]
[TD]ASI[/TD]
[/TR]
[TR]
[TD]9[/TD]
[TD]+4[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]10[/TD]
[TD]+4[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]11[/TD]
[TD]+4[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]12[/TD]
[TD]+4[/TD]
[TD]ASI[/TD]
[/TR]
[TR]
[TD]13[/TD]
[TD]+5[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]14[/TD]
[TD]+5[/TD]
[TD]Imbue Magic (two use)[/TD]
[/TR]
[/TABLE]
Does the power gamer play the same character over and over? Because there is a strongest build. If not... maybe there is other reasons they make a character.
I have a power gamer in my group as well, and they are dedicated to role-playing their character’s concept. It’s not an either-or. He still looks for the story.
There are people who do just play D&D like a board game. That’s sad because it isn’t a board game. It’s roleplaying game. They are doing it wrong.
Building a character that is only good at fighting is like building a character only based around RPing. You’re going to be bored a lot of the time, and not really contributing to the game.
Combat is just a third of the game. A new class really has to look beyond that. The entire spectrum of the game. Building a class based entirely on mechanics and no story hook is boring AF.
Plus... you still need those strong mechanics. And the BEST way to make a class’ mechanics is being inspired by a story. You think about what the archetype should do and add mechanics that do that.
I’d argue the lack of story is why design is going so slow. As a gish, the class only needs to do two things: fight and cast spells. Done. Covered. But almost a dozen other class features are needed and only one has really been brought up, and that’s stolen from another class (the eldritch knight) and probably shouldn’t be used.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.