Headcanon: troll slaves were naked. Most of them were low blood, so don’t need to cover up because their lives are already shame. So, when they’re ready for sell, at most they could wear a ripped cloth, to cover their secrets parts: the cloth is generally dirty white or for the highest one (like jade blood or higher) are coloured, for distinguish the slaves more precious than others. There was a definite way to wear that cloth: indeed, it must be ripped in half the superior part of the fabric, and applied (like a bib) at the troll’s neck. Then, stop it with two or three laps on it, and blocked with the collar handcuffs: the remaining flaps it must be skewered onto troll’s horns, because it means that troll is ‘possessed’ by someone. Cover own horns could have many meanings: from slave possession, to pain or from death grief to shame.