Can you infuse the Arcane Armor's Weapon before you gain Armor Modifications?

Question

An Artificer Armorer acquires the class feature "Arcane Armor" at level 3. With that, the armor provides a special simple weapon (Thunder Gauntlets or Lightning Launcher). Now all of this "Arcane Armor" is one entity (from the perspective of infusions). This changes when you are level 9, then you acquire the "Armor Modifications" class feature, which lets you count your Arcane Armor as four different entities (again from the perspective of infusions).

Can you apply a weapon infusion (Enhanced Weapon) to the special simple weapon (Lightning Launcher) before you get "Armor Modifications" as early as level 3 if no other infusions currently affect the Arcane Armor (no Enhanced Defense, etc.)?

I have seen another post regarding whether or not you can infuse the weapon when you hit level 9 with "Armor Modifications". I am asking explicitly can you do this without the "Armor Modifications" class feature.

Answer 1

You can apply infusions to the weapons of your Arcane Armor after you obtain that feature.

For reference, the relevant excerpts, emphasis mine.

Each of the armor's gauntlets counts as a simple melee weapon while you aren't holding anything in it, and it deals 1d8 thunder damage on a hit. A creature hit by the gauntlet has disadvantage on attack rolls against targets other than you until the start of your next turn, as the armor magically emits a distracting pulse when the creature attacks someone else.

A gemlike node appears on one of your armored fists or on the chest (your choice). It counts as a simple ranged weapon, with a normal range of 90 feet and a long range of 300 feet, and it deals 1d6 lightning damage on a hit. Once on each of your turns when you hit a creature with it, you can deal an extra 1d6 lightning damage to that target.

Both of these weapons count as simple, and are therefore valid targets for the Enhanced Weapon infusion.

Item: A simple or martial weapon This magic weapon grants a +1 bonus to attack and damage rolls made with it.

Since your arcane armor is a single item until level 9, when you obtain Armor Modifications, it would take up the infusion slot for your arcane armor, but it is certainly a valid target for it.

Answer 2

It should work...

Here's why:

Thunder Gauntlets. Each of the armor's gauntlets counts as a simple melee weapon while you aren't holding anything in it, and it deals 1d8 thunder damage on a hit. A creature hit by the gauntlet has disadvantage on attack rolls against targets other than you until the start of your next turn, as the armor magically emits a distracting pulse when the creature attacks someone else.

Lightning Launcher. A gemlike node appears on one of your armored fists or on the chest (your choice). It counts as a simple ranged weapon, with a normal range of 90 feet and a long range of 300 feet, and it deals 1d6 lightning damage on a hit. Once on each of your turns when you hit a creature with it, you can deal an extra 1d6 lightning damage to that target.

The Arcane Armor's special weapons both count as simple weapons. The Enhanced Weapon Infusion requires a simple or martial weapon, so you can use one Thunder Gauntlet or your Lightning Launcher for your infusion.

So your Arcane Armor can be infused with all infusions that require an armor or a single weapon. Of course, you still need the Armor Modification feature to use several infusions on your armor at once.

Answer 3

I thought the same thing on this until reading multiple posts. However, all infusions require touching a non-magical item, so the argument I keep seeing from the people claiming it is not allowed, is that "simple" just means not "martial" from a classification for proficiency.

The logical statement that the thunder gauntlets and lightning launcher are doing elemental damage and magical effect to the creature hit by the attacks, being magical would mean they are not viable infusion targets. Regardless of the D&D Beyond interface restrictions. Some people would claim that they are inventions of science, and therefore not magical. However, the Thunder Gauntlets even use the phrase "magically" in their description:

Thunder Gauntlets. Each of the armor’s gauntlets counts as a simple melee weapon while you aren’t holding anything in it, and it deals 1d8 thunder damage on a hit. A creature hit by the gauntlet has disadvantage on attack rolls against targets other than you until the start of your next turn, as the armor magically emits a distracting pulse when the creature attacks someone else.

At this point, I would argue that by the verbiage of infusing nonmagical and this description, you cannot enhance weapon thunder gauntlets.

However, the entire argument is thrown upside down when you read the armor modifications ability for level 9

Armor Modifications

At 9th level, you learn how to use your artificer infusions to specially modify your Arcane Armor. That armor now counts as separate items for the purposes of your Infuse Items feature: armor (the chest piece), boots, helmet, and the armor's special weapon. Each of those items can bear one of your infusions, and the infusions transfer over if you change your armor's model with the Armor Model feature. In addition, the maximum number of items you can infuse at once increases by 2, but those extra items must be part of your Arcane Armor.

This clearly states that the armor becomes 4 parts and each (including the special weapon) can bear one infusion. This makes it contradictory to everything else.

Outcomes on this could be any of the following:

• The thunder gauntlets are always magical and can never be infused

• Before level 9, when your armor is not considered multiple pieces, you can only imbue the armor with armor specific infusions

• Before level 9, you can imbue the armor with either armor infusions OR enhance weapon, but not both because the special weapon is part of the armor you are wearing

• At level 9, you gain the ability to infuse your special weapon in a way you couldn't before because of your artificer's skill level

There is no clear final final answer from Jeremy Crawford that I have seen. If someone finds a final answer from Jeremy, please share.