As shown below, getting a weapon from a "sleek sword belt" using "slip <weapon>" command will bring you out of hiding. However, you do remain hidden when sheathing the weapon back into the belt.
== Bug: come out of hiding when get weapon ==
> hide
You melt into the background, convinced that your attempt to hide went unobserved.
Roundtime: 2 sec.
H> slip blade in belt
H>
You come out of hiding.
You deftly remove the assassin's blade from your belt.
You silently slip out a silversteel assassin's blade etched with sinuous pictograms from a sleek sword belt with a silversteel longsword hanging from it.
Roundtime: 3 sec.
== Works: remain hidden when put weapon away ==
> hide
You melt into the background, convinced that your attempt to hide went unobserved.
Roundtime: 2 sec.
H> slip blade in belt
You hang your assassin's blade from your belt. It rattles against the silversteel longsword hanging from your belt, and you adjust them.
You silently slip a silversteel assassin's blade etched with sinuous pictograms into your sword belt.
Roundtime: 3 sec.