Can Green-Flame Blade be Quickened? And would the caster be able to attack again?

Question

The spell Green-Flame Blade has a casting time of one action and is also a cantrip. Therefore it seems like a sorcerer should be able to cast it as their action and (by using Quickening) their bonus action. However, Green-Flame Blade allows/requires the caster to make a weapon attack, which would mean that the caster would get to make an additional weapon attack.

The question is then: Is a Sorcerer allowed to make two attacks with the same weapon (as described above)? or does the caster need to be dual-wielding?

if the Sorcerer is able to make the two attacks with one weapon does it need to have the light property?

Answer 1

There is no limit to the number of attacks you can make in a turn. There is a limit to how many actions and bonus actions you can make during a turn. Each action or bonus action that lets you make attacks will specify how many attacks it lets you make.

So, let's break down what you want to do.

Quickening the Green Flame Blade cantrip lets you cast it as a bonus action using the Cast a Spell (bonus) action. As part of this, you make one melee weapon attack. No part of this restricts what weapon you may use, other than a range of 5 ft.

You then use your action to take the Cast a Spell action, again casting GFB. As part of casting this, you make one melee weapon attack. Again, no other restrictions on weapon type.

The light weapon restriction comes from the two weapon fighting rule, which dictates making an attack as a bonus action after using the Attack action. Since you didn't use the Attack action, this rule has nothing to do with what you did.

Yes, you can do this while wielding a single weapon.

Answer 2

The spell description states

As part of the action used to cast this spell, you must make a melee attack with a weapon against one creature within the spell's range, otherwise the spell fails.

I would rule that this means that for a caster to adequately perform the somantic components, a melee attack with a weapon must be made. As you cannot quicken a melee attack, I would say that this would prevent the spell from being quickened.

That said, if a player cast this with still spell and quicken, I would say yes - however this would not grant them two attacks, only the one attack and two spells.