Arcane Gravity

You target one creature that you can see within range, enchanting its equipment with disruptive magic. You cause all magical items carried by that creature to chaotically increase and decrease in weight. For the duration, the creature suffers the following effects:

• Wobbling wand. If the target creature attempts to use a magic item to cast a spell, they must first make a Dexterity saving throw or lose their action and drop the item without casting the spell.
• Wild Weapons. If the target creature attempts to make a weapon attack with a magic weapon and they miss, they drop the weapon and end their turn.
• Heavy Hat. At the start of each turn, if a creature is wearing magical clothing or armor they must succeed on a Strength saving throw or are knocked prone.

At Higher Levels: When you cast this spell using a spell slot of 3rd level or higher, you may select 1 additional target creature for each slot level above 2nd. By using a spell slot of 2nd level or higher, you can also cast the spell on your own magical items to increase dramatically their weight before attacks, or cause the to became so light they can float. 

• Multiattack: By using a spell slot of 2nd level or higher, the spell can be used to increase the weapon speed of currently wielded magical weapons by lowering their weight, granting a 2 extra strikes per turn, for the next 2 turns.
• Thundering Blow: By using a spell slot of 2nd level or higher, the user can increase the weight of a magical weapon they are wielding during an attack, granting extra damage to the attack. It stays active for 3 turns. Add 2d8 to the weapon's original damage.

 Credit: This is an altered version of Zee Bashew's Arcane Gravity spell. (Juryrigged Spellbook) Arcane Gravity D&D 5e). The video description has the original spell.