If the UA Wild Soul barbarian's Wild Surge table causes a greatsword to gain the light property, can it be dual-wielded?

Question

The playtest Wild Soul barbarian subclass (from Unearthed Arcana: Barbarian and Monk has the Wild Surge feature at 3rd level, causing magic to erupt from the barbarian when they rage.

Row 7 in the Wild Surge table lists the following effect:

Shadows weave around a weapon of your choice you are holding. Until your rage ends, your weapon deals psychic damage instead of its bludgeoning, slashing, or piercing damage, and it gains the light and thrown properties with a normal range of 20 feet and a long range of 60 feet. If you drop the weapon or throw it, the weapon dissipates and reappears in your hand at the end of your turn.

By default, a greatsword (other big sticks are available) has both the two-handed and heavy properties. The description of the two-handed property says:

This weapon requires two hands when you attack with it.

The description of the heavy property says:

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.

But if the barbarian's Wild Surge results in option 7, then it seems it would gain the light property as well:

A light weapon is small and easy to handle, making it ideal for use when fighting with two weapons.

Going by the mechanics alone, I see no problem between a weapon being both light and heavy, since a Small creature would have disadvantage and you could dual-wield. But thematically I have a problem with something being light AND heavy since, ya know, they're both opposite ends of the "how heavy" scale. I guess the important question here is: how heavy is it?

The mechanical problems come with light and two-handed. Two-handed sort of rules out dual-wielding unless you have more than two arms (but I've seen this be overruled in official books, such as when a giant wields it in one hand), but light says that it's perfect for dual-wielding. So what happens in this case?

My interpretation is that you can't dual-wield because of the weight and heftyness, but light cancels that out, but I may well be wrong.

Answer 1

The 2-handed property makes the light property irrelevant

As covered in this question about the light property, the only function of the light property is to enable the bonus action attack of two-weapon fighting (TWF), and the light property doesn't necessarily have to do with weight (e.g. some light weapons are heavier than some non-light weapons). However, it's not possible to use TWF with a 2-handed weapon (even if you somehow have more than 2 hands), because the trigger for TWF is:

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 the other hand.

Hence, you could have 4 arms and be holding a two different 2-handed weapons, but RAW you still couldn't use TWF with them, because you must be holding each weapon in a single hand to use TWF. So, since TWF is unusable with 2-handed weapons, and the only function of the light property is to enable TWF, adding the light property to a 2-handed weapon has no effect at all.

(That being said, the TWF rule is clearly written with the assumption of having exactly 2 hands, and I don't know how much sense it makes to apply it to creatures with different numbers of hands. I don't know of any playable race or class feature that provides more than 2 hands that can wield weapons.)

Heavy, light, and thrown are all mutually compatible

As for a weapon that is both heavy and light, while it seems odd, RAW there is no mechanical conflict between the two properties.

Finally, there is no problem with adding the thrown property to a 2-handed or heavy weapon.

Answer 2

From the main text of the article you cited:

We invite you to give these subclasses a read, try them out in play, and let us know what you think. Watch the D&D website for a new survey and let us know there what you think of today’s Unearthed Arcana.

This Is Playtest Content

The material in Unearthed Arcana is presented for playtesting and to spark your imagination. These game mechanics are in draft form, usable in your D&D campaign but not refined by final game design.

Your question is a perfect example of the many bugs and edge cases that playtesting is intended to find.

Unfortunately, it also means that there's very little in the way of canon or RAW to fall back on in helping answer the question. You will need to decide among yourselves at your table to decide how to adjudicate the conflicting tags, and there is support for both:

• There's no conflict; the light property just makes a weapon suitable for two-weapon fighting, while the two-handed property makes it unusable for two-weapon fighting.
• "Holy...! When I raged, my sword just got turned into a psychic shadow blade, and it's light enough to throw and automatically comes back! KICK A--wait, what do you mean I still have to use both hands!? This sucks..."

Answer 3

The Light and Two-Handed tags are contradictory.

The description of the Light tag is:

Light. A light weapon is small and easy to handle, making it ideal for use when fighting with two weapons.

If a weapon requires two-hands then it cannot be "ideal for use when fighting with two weapons."

The section on How to Play offers the following to deal with conflicting rules:

That said, many racial traits, class features, spells, magic items, monster abilities, and other game elements break the general rules in some way, creating an exception to how the rest of the game works. Remember this: If a specific rule contradicts a general rule, the specific rule wins.

The issue is the rules governing Light are no more specific than the rules Two-Handed.
Both cannot be true but it is not obvious which should be dominant.

I would argue that Light should take priority in the case of the Barbarian's Wild Magic Surge. While the tag itself is not more specific than Two-Handed, the feature granting it is. We can see from regular weapon design that Light and Two-Handed are usually mutually exclusive. Wild Magic Surge creates a specific exception to this so its effects overrule the general rule for Two-Handed weapons.

In terms of game play this grants around 1d6+rage bonus damage per turn. This is in line with many of the Wild Magic Surge options that appeared in Path of Wild Magic, the finalized version of the Path of the Wild Soul.

For example the Path of the Wild Magic from Tasha's had the following possibility:

A bolt of light shoots from your chest. Another creature of your choice that you can see within 30 feet of you rust succeed on a Constitution Saving throw or take 1d6 radiant damage and be blinded until the start of your next turn. Until your rage ends, you can use this effect again on each of your turns as a bonus action.

Is 2-4 points of damage about equal to inflicting the blinded condition? I think so. Considering many of the Path of the Wild Soul/Wild Magic features were boosted between UA and TCE this provides support that allowing Two-Weapon fighting with a Great Axe is balanced as a part of a Wild Magic Surge.