From ErfWiki

Proposed Canon

The Clotheshorse is a unit used by Haggar. Their appearance and abilities are unknown. Jetstone traded Count Topotato to Haggar for two Clotheshorses and a tun of mead.

Speculation

Clotheshorses are likely mounts. They may come equipped with fancy livery, which may provide some form of bonus in combat. This may be a form of Natural Dollamancy, perhaps allowing them to equip different kinds of livery, each with a different kind of effect.

Real World References

A Clothes Horse is an individual who has enjoys buying clothes and maintaining an extensive wardrobe.