Quickened Spell vs Spellsword

[WaggleDagger]

So the "spellsword" or "gish" has always been a popular character in games with both magic and martial prowess. Weaving spell casting and sword slashing are always fun. However, in 5e, it seems the developers intended three options for spellswords:

The College of Valor Bard
The Eldritch Knight
and
The "Bladelock"

Not going to touch the Bladelock as of right now, as it's melee power is lacking without some weird workarounds and one of the new invocations in Unearthed Arcana. The Eldritch Knight is a fantastic 1/3 magic user with some fun limitations and the ability to make one attack as a bonus action after a spell, while retaining the four attacks of the fighter. The Valor Bard gets the extra attack feature, as well as the ability to make an attack as a bonus action after casting.

However, both of these classes allow a single melee attack as a bonus after a spell. Wouldn't it be more "spellsword" to make the spell faster and still get a full melee attack?

It seems silly but the Sorcerer seems to make the best Spellsword to me. Using Quickened Spell (which isn't that many sorcery points) allows any spell to be cast as a bonus action, leaving a full action for the attack. The devs seemed to want to limit bonus action casting because you can only cast a cantrip as a full action afterwards, but it says nothing about attacks. Using a lvl 14 valor bard and 6 sorcerer would grant you a full spellcasting slot array, the extra attack feature, and plenty of spell slots to melt down into more quickened spell castings. This allows for a full 9th level spell to be cast as a bonus action then still take TWO melee attacks as a regular action. Or you could try 11 fighter, 9 sorcerer giving less slots, but a full THREE attacks after a bonus casting. This is make even crazier by the "Stone" based sorcerer in Unearthed Arcana which focuses even more on melee attacks.

Am I missing something here? A rule about attacks and bonus spells perhaps? It just seems the developer intended spellsword classes fall flat before the power of Quickened Spell.

[DivisibleByZero]

It's about balance.
One cantrip (or later, one spell) and a single attack doesn't break anything. Cantrips don't scale as well as a fighter's combat ability, so adding a single attack to one is fine. By the time that you can do the same with a full spell, that spell is probably powerful enough so that the one attack added isn't changing much.
A full attack with a cantrip/spell included, on the other hand, is crazy powerful. Consider that a fighter gets a similar ability via Action Surge, and that's limited to once per short rest.
The sorcerer, being the exception via quicken, is forced to use a limited resource to do the same, and he's relegated to only a) another cantrip, b) a single attack, or c) two attacks if he has a bloodline with extra attack included.
The "spellsword" can do it all day without spending any extra resources, but can only add a single attack.
Because like I said, it's about balance.

(although I will admit that Bladesingers and other full casters with extra attack should probably be able to choose a war-magic-like substitute instead of EA if they want to, because that is indeed more thematic)

[Byke]

Am I missing something here? A rule about attacks and bonus spells perhaps? It just seems the developer intended spellsword classes fall flat before the power of Quickened Spell.

Nope you aren't missing anything and I loved the gish/swordmage play style in 3.5 and the best that fit the mold in 3.5 is Paladin / Sorcerer here is a great guide.

http://www.giantitp.com/forums/showthread.php?502673-Unlimited-Blade-Works-The-Guide-to-the-Ultimate-Paladin-Sorcerer-Multiclas

Granted with the new UA invocation haven't explored Hexbalde or Fiend lock (1-2 fighter/18-19 lock)

[Specter]

The difference is, as you said, resources, and the fact that Sorc multiclasses with martials take a long time to be good. War Magic is forever, while sorcery points are a tax.

At level 10, for instance, EK can attack and cast a cantrip with a save disadvantage every turn. A sorcerer 10 can attack and quicken a leveled spell 5 times. You could of course expend slots to create sorcery points, but that eats up your bonus action and makes spells drain much faster. A Sorcerer 5/Fighter 5 attacks twice, but has only two quickens available.