Enlarge/Reduce Equipment

(Originally created by the ancient archmage Aksa, this spell is now virtually extinct across the Flanaess. Following the recovery of the original formula, the Circle of Eight quietly seized and destroyed all remaining scrolls, to prevent Tenser from ever learning of its existence. They feared it would lead him to completely degrade the Circle's standards of "arcane decency" even more than he already is. Today, the spell is known only outside the region, frequently dismissed by Greyhawk and Forgotten Realms wizards alike as completely useless to a wizard and a waste of arcane energy)

You touch a nonmagical piece of equipment that can be worn or wielded (such as a weapon, armor, or a shield) that is not currently being worn or carried by an unwilling creature. You cause the object to grow or shrink by one size category for the duration.

If a creature wielding or wearing this targeted equipment undergoes a size change from a class feature (such as the Fighter's Giant's Might or the Barbarian's Giant's Havoc), this spell's physical properties—including its modified weight, dimensions, and damage dice—completely supersede the standard equipment scaling of those features.

P.S. Casters must consider the physical reality of nonmagical equipment, such as how the item is carried or stowed, the quality and durability of its materials, and the maintenance required to keep it from degrading.

Enlarge

The object’s size category increases by one (e.g., Medium to Large, or Large to Huge). Its dimensions double, and its weight is multiplied by eight.

Weapons: The weapon is scaled up for a larger tier of attacker. Its damage dice are multiplied based on its new size category: doubled if it becomes Large, tripled if it becomes Huge, and quadrupled if it becomes Gargantuan (relative to its standard Medium/Small base damage).

Wielding Rules: A creature has disadvantage on attack rolls with a weapon that is sized for a larger attacker. This disadvantage cannot be canceled out by gaining advantage. A weapon sized for an attacker two or more sizes larger than the wielder is too big to be used at all.

Shields/Armor: The armor or shield increases by one size category. It can be worn by a creature of that larger size category, offering its standard AC bonus. It provides no AC benefit to a creature smaller than its new size category.

Reduce

The object’s size category decreases by one (e.g., Large to Medium, or Medium to Small). Its dimensions are halved, and its weight is reduced to one-eighth of its original weight.

Weapons: The weapon is scaled down for a smaller tier of attacker. If its size category becomes Tiny, its damage dice are halved (rounded down, to a minimum of 1 die).

Wielding Rules: A creature has disadvantage on attack rolls with a weapon that is sized for a smaller attacker. This disadvantage cannot be canceled out by gaining advantage. A weapon sized for an attacker two or more sizes smaller than the wielder is too small to be used at all.

Shields/Armor: The armor or shield decreases by one size category. It can be worn by a creature of that smaller size category, offering its standard AC bonus. It provides no AC benefit to a creature larger than its new size category.

When the spell ends, the equipment safely returns to its original dimensions. If it is inside a space too small to accommodate its normal size, it expands to fill the available space without causing damage, stopping its growth if it meets a solid barrier it cannot break.

At Higher Levels. Casting this spell at 5th level allows it to target a magical weapon, shield, or set of armor, provided its only magical property is a bonus to attack rolls, damage rolls, or Armor Class (such as a +1 weapon or +1 armor).