If a staff with a Shifting rune is transformed into a gauntlet, can you cast spells from the staff/gauntlet while wielding another weapon?

Magic staves can have weapon runes applied to them. One rune is a Shifting rune, which lets you transform the weapon into a different weapon. If I use a Shifting rune to transform a staff into a Gauntlet, then pick up a sword with that hand, can I still cast spells from the staff/gauntlet in this state?

How can I replicate this effect of the Infinity Gauntlet using official material?

I am a GM searching for some means (spell, magic item, artifact, etc) of replicating the power granted by the notorious Infinity Gauntlet as depicted in Marvel’s Cinematic Universe. The effect I’m searching for in the game I am going to run as GM isn’t “demicide” but is (if anyone recognizes my name and will be in my game spoiler below):

The 9th Level Spell Wish does not seem to suffice due to this clause in the rules for Wish:

You might be able to achieve something beyond the scope of the above examples. State your wish to the DM as precisely as possible. The DM has great latitude in ruling what occurs in such an instance; the greater the wish, the greater the likelihood that something goes wrong.

Emphasis added.

I’m looking for something reliable, not a monkey paw that Wish seems to function as when anyone attempts to use it for effects of this scope.

Something that ties into established D&D lore rather than “oh yeah, it’s like the movie, but in D&D”.

If there is nothing even remotely like the Infinity Gauntlet in any official D&D 5e material, or Unearthed Arcana, then are there any official rules or guidelines on expanding the scope of a spell like Disintegrate to target massively large numbers of targets? I could extrapolate from there.

CLARIFICATION: it doesn’t have to have “collect sub-components” as the Infinity Gauntlet needed Infinity Stones to be collected from all over the universe. The important part is if there is already anything or anyone in DnD5e official that has such power.

Can a Spiked Gauntlet worn by a polearm-wielding Fighter allow him to do attacks of opportunity with it?

If a fighter is wearing Spiked Gauntlets wielding a Ranseur, does he threaten both the 5′ area around him with the piked gauntlets and the 10′ with the Ranseur which would allow him to make an attack of opportunity with either weapon depending on the distance of his opponent?

How does wearing a locked gauntlet interact with failing a disarm check?

In 3.5, wearing a locked gauntlet provides a +10 bonus against being disarmed. If you attempt to disarm an opponent and fail, your opponent can attempt to disarm you in response. So locking your weapon into a gauntlet directly mitigates part of the risk of attempting to disarm your opponents.

In Pathfinder, however, the bonus from a locked gauntlet is +10 to CMB against being disarmed. If you attempt to disarm an opponent and fail by 10 or more, you automatically drop your weapon. As your CMB never comes into it, RAW suggests a locked gauntlet provides no defense against this – yet removing a weapon from a locked gauntlet is supposed to be a full-round action!

This seems counter-intuitive, to say the least. Is this really the interaction between a locked gauntlet and a failed disarm attempt?