Sorry that I didn't respond earlier, just got back from a vacation. Here we go:
They can summon any normal familiar, but have additional options that are superior in practically every way. As soon as you say "I turn my familiar into a Pseudodragon/Imp/Quasit/Sprite", I know that you're a Pact of the Chain Warlock.
Only if they are pact of the chain. Pact of the tome are limited to normal familiars.
Probably Fey Touched to get Hex and misty step, and probably Shadow Touched or Magic Initiate to get Inflict Wounds and Invisibility.
But again, those are feats, not a part of your class's identity.
They are feats, one of which I took instead of an ASI with the Rogue feature. The point is I can cast a wide variety of spells off multiple spell lists and about the same number of castings as a full caster.
So you agree with me that there is a line. You just think that the line is "barbarians that are adept spellcasters" instead of my own line.
There is a line, but your example is not it IMO. Barbarians do not make good spellcasters but bladesingers do make good Gish characters.
There's a difference between telling a Rogue that they're allowed to be excellent at almost any skill that they want (as is a part of their theme) and telling an Arcane Gish that they have to spend their Feats and/or race to match their theme that they want
This is not true, there are 17 skills. A Rogue has 11 skills to choose from and another 2 he can get IF he takes the scout subclass. If he wants to be great at any of the other 6/4 skills in the game he is going to need a race, background and/or feat to do it.
The point is he can and he can do that relatively easily.
You may not see giving up 2-3 feats a major tradeoff to emulate a part of your character's core identity, but I do. I wouldn't play a Cleric if I had to spend 8 levels and 2 feats in order to get access to Channel Divinity.
You are not "giving up" any feats, you are building your character.
Paladins don't have to make any trade like that. Neither do Rangers, Artificers, or any other class. An Arcane Gish class wouldn't force a character to make that choice. That's the point.
Yes they do. They give up things all the time to get what you want. Someone who takes GWM "gives up" +2 in an abilty. Someone who takes PAM "gives up" the ability to do +10 on damage, someone who takes +2 in strength "gives up" the ability to make a BA attack with the back of his polearm.
This is no different than those choices.
The Rogue who takes mobile feat (which is very, very common) gives up a third of his cunning action and in an example that is completely appropriate if he is a swashbuckler subclass he gives up the "main core feature" of his subclass.
No, because none of the Barbarian's main features (ie Rage) cease to work when they're wearing medium armor. A major complaint that people have about the Battlerager barbarian is that their core features only work if they're Spiked Armor, which can cause them to have a worse AC than if they weren't wearing armor. This is a similar situation.
No unarmored defense, which is a core feature, ceases to work.
This is irrelevant to the argument. The point was that Rage and Bladesong are comparable. If someone wants there to be a heavily armored barbarian subclass, it would not be a valid argument to tell them "just play an official subclass and wear heavy armor! You're not giving up that much in exchange!!!"
Unarmored defense and bladesong are similar. Rage is not mechanically similar at all. Unarmored defense and bladesong both give another ability as a bonus to AC. Bladesong is weaker though because it is limited use. Yet the Barbarian gives up unarmored defense and that is not a problem.
Keep in mind that Weapon Master and Moderately Armored are both restrictive half-feats. A character that takes those feats is restricted to the ASIs that they allow, instead of the base ASI allowing any ability score to be increased.
Yes. But this presumes you are going to take it instead of increasing strength.
Have you even read the Paladin or Ranger Class? Paladins get All Armor proficiencies, Shields, and Simple/Martial weapon proficiency. Rangers get all of that, but don't get Heavy Armor (which I feel is a mistake). They both get the same amount of ASIs as every non-Fighter, non-Rogue class in the game.
The Paladin has an extremely limited number of smites and they are far inferior to casting a spell as part of an attack. Being able to do this just once a day below level 10, while also having all weapons and armor would make such a character substantially more powerful than a Paladin.
Merging a spell with a weapon attack. More specifically, being able to cast a spell, but instead of releasing it, trapping it inside your weapon to be released when you next hit a target with the magic weapon you're wielding.
There would be a limiting feature (action economy, concentration, and spell slots), but it would eventually get better as you reach higher levels, just like how Divine Smite is limited by spell slots until Improved Divine Smite comes along at level 11.
Don't criticize a feature for being OP that you haven't seen yet, please. If you want me to show you the rough draft feature, just ask, and I'll freely give it. However, I'm not very inclined to do so with you bashing it for being OP with absolutely no idea on how I'd actually implement it.
I am going by what you used as an example. You are taking a spell that does MORE damage then a smite and letting it be loosed as part of any attack (not just a melee attack), that spell is one example of many as you can do basically anything that a spell you have can do and you are breaking action economy to do it. It is heads and tails above divine smite.
If you compare this to the Paladin smite:
1. The Paladin smite can only do radiant damage to one target, they can't do anything else with their smites. It is limited. The ability you propose is limited only by the effects of the spells you have.
2. The example you gave already does more damage than a smite and this is going to be more lopsided at higher levels (fireball 8d6 vs many foes or smite 4d8 against 1 foe)
If you really want something that is balanced, how about this as a template:
Use the Paladin template, but have "spellstrike" and a unique spell list and let you use a weapon as a focus.
Spellstrike: After you hit with an attack you can cast one of your spells as part of the attack, the attack gives the visuals and appearance of the spell cast (i.e. the theme) but it only damages or affects the target you hit and any damage caused by the spell is capped at 1d8+1d8 per spell slot expended.
This gives you mechanics that are only a little more powerful than one of the best martial classes in the game while having the theme you are looking for because you will actually have a fireball blowing up (it will just only be damaging one person)
Replace Lay on Hands with ritual casting. Get rid of divine sense since your smite has varied uses and damage types and is more powerful than standard divine smite. Replace Aura of protection with a bonus on your saves vs magic.
That would be actually be pretty balanced with a Paladin through the first 10 levels or so, but my guess is it is not powerful enough for you.
