Possible colored equipment cycle. See Red Cape

I would personally outright ban that trigger. It's just totally dumb with Suit Up. You can have two Suit Up creatures, this, untap everything, but the board state is otherwise mysteriously identical. It's odd, and kinda like the Oblivion Ring trick. Not intuitive, or fair.

This version seems more fair; "Whenever White Cape becomes attached to a creature for the first time this turn, untap that creature." Once more not a fan of colored equip costs on colorless equipment.

Alternatively it could be "When equipped creature deals combat damage, untap it." This pulls off the same pseudo vigilance without untapping the whole team.

Colored equip costs are not necessary, but i prefer them to colored equipment if it ever comes to it. The main reason I like them is that it allows us to have control over where these show up, otherwise the strongest equipment might just get picked away from the equipment player.