dnd 5e – Are extra effects considered weapon damage on a sword of sharpness?

Sword of Sharpness maximizing damage only applies when attacking objects and only applies to weapon damage dice


Sword of Sharpness only applies to objects

This is clear from the Sword of Sharpness description which states (emphasis mine):

When you attack an object with this magic sword and hit, maximize your weapon damage dice against the target. (…)

Thus, any feature that only triggers when attacking a creature cannot even apply here. Sneak Attack is one such feature as gone over in the following:

The feature, for reference, states the following (emphasis mine):

(…) you can deal an extra 1d6 damage to one creature you hit (…)

Because Sneak Attack only works on creatures and Sword of Sharpness only works on objects, these cannot occur at the same time. (Probably)…


Sword of Sharpness only applies to weapon damage dice

This, again, is clear from the description (emphasis mine):

When you attack an object with this magic sword and hit, maximize your weapon damage dice against the target. (…)

Because of this, features that add damage to an attack that do not count as adding weapon damage dice have no interaction with a Sword of Sharpness. We have some questions related to this:

The first two are about features which explicitly apply to weapon damage dice (like the Sword of Sharpness) and the last one is a question about a feature that explicitly adds to your weapon damage dice. Most features do not explicitly add to your weapon damage dice and thus do not count as weapon damage dice and thus are not maximized by a Sword of Sharpness.

The Sage Advice Compendium states the following:

Q. If you use Great Weapon Fighting with a feature like Divine Smite or a spell like hex, do you get to reroll any 1 or 2 you roll for the extra damage?

A. The Great Weapon Fighting feature—which is shared by fighters and paladins—is meant to benefit only the damage roll of the weapon used with the feature. For example, if you use a greatsword with the feature, you can reroll any 1 or 2 you roll on the weapon’s 2d6. If you’re a paladin and use Divine Smite with the greatsword, Great Weapon Fighting doesn’t let you reroll a 1 or 2 that you roll for the damage of Divine Smite.

From this we can see that features like Divine Smite, which do add extra damage but do not explicitly add extra weapon damage do not count as weapon damage dice for the purposes of things like the Sword of Sharpness. The Cavalier Fighter’s Unwavering Mark feature is, as far as I’m aware, one of very few features which explicitly adds to your weapon damage dice.