After lightning struck the cliffs, the ore became iron, the iron became steel, and the steel became greaves. The lightning never left.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

When you spend most of your time running for your life, it pays to invest in quality footwear.

Duskmourn: House of Horror Commander

Mystery Booster 2

"I love these boots so much, I'm never taking them off."

Secret Lair Drop

Modern Horizons 3 Commander

Outlaws of Thunder Junction Commander

If a creature enters the battlefield under your control and gains haste, but then loses it before attacking, it won't be able to attack that turn. This means that you can't use one Lightning Greaves to allow two new creatures to attack in the same turn.

You can't simply unequip Equipment from a creature. If Lightning Greaves is attached to the only creature you control, you won't be able to attach other equipment to it (or target it with anything else) until you have another creature onto which you can move Lightning Greaves.