could this work?
No. All weapons with the "heavy" property have the two-handed property as well. Here's exactly what each property does (PHB 147):
Heavy. Small creatures have disadvantage on attack rolls with heavy weapons. A heavy weapon's size and bulk make it too large for a Small creature to use effectively.
Two-Handed. This weapon requires two hands when you attack with it.
The heavy property itself isn't a problem here, but the two-handed is. Since all heavy weapons are also two-handed, you must use two hands to wield them. The enlarge spell doesn't give you the ability to wield a two-handed weapon in one hand, even if that weapon wasn't enlarged with you. Your DM might allow it, but it's certainly not part of the Rules As Written.
So what can you dual wield, then? Here's the rules on two-weapon fighting (PHB 195):
When you take the Attack action and attack with a light melee weapon that you're holding in one hand, you can use a bonus action to attack with a different light melee weapon that you're holding in one hand. You don't add your ability modifier to the damage of the bonus attack, unless that modifier is negative.
Based on this, you can only dual wield light melee weapons. You don't even need the two-weapon fighting style, since all the fighting style does is allow you to add your ability modifier to the bonus action attack. There is a way to get around the "light" limitation, namely the Dual Wielder feat (PHB 165, emphasis mine):
You master fighting with two weapons, gaining the following benefits:
- You gain a +1 bonus to AC while you are wielding a separate melee weapon in each hand
- You can use two-weapon fighting even when the one-handed melee weapons aren't light
- You can draw or stow two one-handed weapons when you would normally only be able to draw or stow only one.
This feat allows you (among other things) to use any one-handed melee weapons for two-weapon fighting.
In conclusion, you're not going to be two-weapon fighting using greatswords, even if you're enlarged. The closest you're going to get would be two longswords with the Dual Wielder feat
Side note: If you want to do two-weapon fighting purely from an optimisation perspective, you may want to reconsider. It is generally accepted as one of the weaker playstyles, as it uses your bonus action to be effective (needed to cast smite spells on a paladin, for example), and still can't quite compete with great weapon fighting, especially if you factor in the Great Weapon Master feat. It doesn't fall completely behind other playstyles, so if you want to do it because of a character concept, go ahead. But if it's exclusively for optimisation, it might be better to just use a single greatsword.
I didn't do any math, just going off of experience building quite a lot of encounters here. If an exact calculation is what you want, leave a comment and I'll delete this answer.
Coinflip encounter
This encounter will come down to the initiatives rolled. With 13 AC and 28 hit points, neither of the swarms should live more than one attacking round from the party at level 6, even taking into account resistances. They should however take up approximately that round of attack by the players.
Which leaves the Living Spellbook, which gets a practical one round of free attacks because the players will be dealing with the swarms. If they're careless or unlucky (aka, you felt like giving them a hard time), the book will use two multiattacks on the sourcerer or artificer, who should go down fast. At that point the combat depends on whether they were able to dispel the mage armor. If the swarms got off an attack before dying, I'd say those chances are low. Otherwise they are high and the fight should be a breeze for the barbarian and fighter (the arcane explosion should do approximately zero agains them with a Strength saving throw).
So the 2 scenarios I see happening are:
Swarms have relative high initiative
- The swarms attack the artificer and sourcerer for about 50% of their HP
- The swarms die
- The Living Spellbook effectively takes out the artificer and sourcerer out of the fight
- Mage armor isn't dispelled, your barbarian and fighter have a hard time, but should barely win out before any deadly casualties. Bad dice rolls for the player result in a loss
Swarms have relative low initiative
- Swarms die immediately
- Sourcerer dispels mage armor on the Living Spellbook
- Living spellbook becomes a glass cannon with 14 AC, which both the barbarian and fighter easily break
- Fight is a breeze, biggest risk is a small paper cut by one of the twirling paper sheets
Best Answer
I believe you are somewhat mistaken about Silvered Weapons:
Werewolves and fiends are resistant to non-magical weapon attacks that aren’t silvered. There may be more creatures that are weak to silver but those are two examples. Silver-coated weapons are not considered magical; it’s just that the creature they are hitting is weak against them.
However, you might be able to do this using the barbarian's Path of the Battlerager (SCAG, p. 121), though it's normally restricted in the Forgotten Realms only to dwarves.
Battleragers gain the ability to use spiked armor, described in a sidebar on the same page, as a weapon. The 3rd-level Battlerager Armor feature lets them use a bonus action while raging to attack with their spikes, and automatically do damage when grappling creatures.
And at 14th level, Battleragers get the Spiked Retribution feature:
So if your DM allowed you to either plate your spikes or make them entirely out of silver, you could in fact hurt a Werewolf or Fiend with your armor. I would imagine the cost to coat or make the spikes silver would be very high.
So if you happen to be a Dwarf Barbarian Battlerager in a campaign that is heavy in Werewolves or Fiends, and you have a lot of gold, it would be in your best interest to plate your spikes with silver. Actually, it sounds like a lot of fun.