Is a hand wearing a spiked gauntlet considered to be "free" for the purposes of somatic components?

Question

The SRD's list of weapons includes the spiked gauntlet. The given rules are:

Gauntlet, Spiked

Your opponent cannot use a disarm action to disarm you of spiked gauntlets. The cost and weight given are for a single gauntlet. An attack with a spiked gauntlet is considered an armed attack.

In order to cast spells with somatic components, you must have at least one free hand, per the SRD:

Somatic (S)

A somatic component is a measured and precise movement of the hand. You must have at least one hand free to provide a somatic component.

Is a hand with a spiked gauntlet on it considered to be "free" for this purpose?

Answer 1

First, regular gauntlets. When described as weapons, they are given this description:

Gauntlet

This metal glove lets you deal lethal damage rather than nonlethal damage with unarmed strikes. A strike with a gauntlet is otherwise considered an unarmed attack. The cost and weight given are for a single gauntlet. Medium and heavy armors (except breastplate) come with gauntlets.

Note that medium and heavy armors come with gauntlets by default, which the various armor descriptions indicate:

Banded Mail

The suit includes gauntlets.

Chainmail

The suit includes gauntlets.

Full Plate

The suit includes gauntlets, [...]

Half-Plate

The suit includes gauntlets.

Scale Mail

The suit includes gauntlets.

Splint Mail

The suit includes gauntlets.

Each of these armors indicates an arcane spell failure chance, from 25% to 35%.¹ Arcane spell failure’s definition is

Arcane Spell Failure

Armor interferes with the gestures that a spellcaster must make to cast an arcane spell that has a somatic component. Arcane spellcasters face the possibility of arcane spell failure if they’re wearing armor. Bards can wear light armor without incurring any arcane spell failure chance for their bard spells.

Casting an Arcane Spell in Armor

A character who casts an arcane spell while wearing armor must usually make an arcane spell failure roll. The number in the Arcane Spell Failure Chance column on Table: Armor and Shields is the chance that the spell fails and is ruined. If the spell lacks a somatic component, however, it can be cast with no chance of arcane spell failure.

Shields

If a character is wearing armor and using a shield, add the two numbers together to get a single arcane spell failure chance.

It seems to me that if a character using one of these armors that are assumed to include gauntlets still has a 65%-75% chance of successfully casting an arcane spell, and that the chance of failure here applies only to arcane spells, gauntlets cannot make somatic gestures impossible. Harder, perhaps; they probably figure into the relatively-high arcane spell failure chances of these armors. But not impossible.

Basically, the game simply has too many rules for determining your chance of successfully casting a spell while wearing armors that include gauntlets for gauntlets to preclude spellcasting. If they did that, all those rules wouldn’t be necessary and I would expect some kind of “N/A” entry in their ASF column, and a note in the rules for arcane spell failure.

Finally, we have the locked gauntlet:

Gauntlet, Locked

This armored gauntlet has small chains and braces that allow the wearer to attach a weapon to the gauntlet so that it cannot be dropped easily. It provides a +10 bonus on any roll made to keep from being disarmed in combat. Removing a weapon from a locked gauntlet or attaching a weapon to a locked gauntlet is a full-round action that provokes attacks of opportunity.

The price given is for a single locked gauntlet. The weight given applies only if you’re wearing a breastplate, light armor, or no armor. Otherwise, the locked gauntlet replaces a gauntlet you already have as part of the armor.

While the gauntlet is locked, you can’t use the hand wearing it for casting spells or employing skills. (You can still cast spells with somatic components, provided that your other hand is free.)

Like a normal gauntlet, a locked gauntlet lets you deal lethal damage rather than nonlethal damage with an unarmed strike.

Note how locked gauntlets specifically call out that they do not count as a free hand, but that you could still have your other hand free. This is exactly what I would have expected regular gauntlets to say if they prevented your hand from counting as free. They do not, however, say that.

Finally, actually getting to spiked gauntlets properly,

Gauntlet, Spiked

Your opponent cannot use a disarm action to disarm you of spiked gauntlets. The cost and weight given are for a single gauntlet. An attack with a spiked gauntlet is considered an armed attack.

Nothing here says that spiked gauntlets interfere with your hand any more than regular gauntlets... but then, nothing says that spiked gauntlets work “like” gauntlets or any such thing, and weapons usually do take up a hand. To that, I have previously described that situation as ridiculous, and I stand by that. Spiked gauntlets should work just like gauntlets, but with spikes (piercing damage, larger damage die), even if the rules fail to actually indicate that.

So unless your spiked gauntlet is also locked—which is probably a thing you can do—it should be free to cast spells.

1. _{Hide armor is a non-breastplate medium armor, so it may or may not have gauntlets—it doesn’t seem to have an individual entry. I’m not sure the word “gauntlet” can really apply to what are really just heavy leather gloves. Anyway, if it does that would drop the lower end of the ASF range to 20%.}

Answer 2

Maybe. There are two kinds of gauntlets.

First off, a Gauntlet is heavy and that by itself hinders movement. Any gauntlet serves the purpose of protecting the hand against heavy impact. They're also made of very thick and heavy layers of iron, since it's an area bound to be cut during a fight.

Most gauntlets are "Locked" (That means, there are very few available hand positions, usually with a very small ammount of mobility on purpose), particularly those meant to be a piece of a armor. Those are hard gripped, almost trapped into the "holding" finger position to prevent being disarmed, or as terrible as it seems, to the unfortunate case of you breaking your hand. (Where you will still hold your weapon in a almost-fightable state)

Spiked gauntlets serve a similar purpose. It should be a solid and hard to move piece, because it is meant to protect your fingers in combat, both from slicing and from literally breaking your fingers against solid surfaces. So realistically, those should be "locked as well", but in D&D they come in both flavours. If this gauntlet itself came from an armor, it is almost certain to be locked and prevent movement. Otherwise we have several examples of spiked gauntlets being described as a fully mobile weapon (See a Battlerager's gauntlets that leaves the hand absolutely free and favor mobility, also meant for grapple attacks)

It comes to the DM decision of WHICH gauntlet it is, where it came from, and what is it meant to do. Is it locked? If yes, it definitely blocks somatic movement entirely. Is it "free" and was build for mobile combat including grapple maneuvers? Then it impacts 0% in somatic component and spell failure.