Lightning Greaves

Artifact — Equipment

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

With a surefooted twist of his foot and a measured shift of his weight, the warrior was upon them.

Illustrated by Borja Pindado · Star Trek Commander (TRC)

2020-08-07
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 to which you can attach Lightning Greaves.
2020-08-07
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.