I think an easy way is to make it like a cabinet, but with a much smaller solid storage size as to only hold maybe 4-5 pieces of armor. I’m assuming that the cabinet is set to only hold clothes when I say this, so I’m assuming that the capability can also be used here. Still assuming.
Assumptions are well founded, that's pretty precise way of looking at it. Prepackage the "armor cabinet" with a soldiers uniform in a barracks assigned to a squad, and they will instantly get changed into their clothes there & then rather than grab individual pieces.
The general idea was that 1 weapon rack can be assigned 2-3 weapons & a 100 (or a rough estimate) bolts each given that logistically 1 weapon to each rack solely would (1 weapon & two stacks of 50 bolts would work though too in a balanced way) be a bit too close to a cabinet or a plinth's ability.
Say that you embark, you bring - Two battleaxes, a quiver & a 100 copper bolts, & 3 sets of leather armor, plus two copper crossbows, 1 hunter with moderate crossbow skill & 'Teacher' and a dwarf trained in hammering, both the hammer dwarf & woodcutter have teaching skills too to cross-train each other.
So you'd get your carpenter to craft you four weapon racks and three armor racks (per dwarf), three weapon racks goes into the barracks & 1 goes into the hunter's room, the hunter brings back some food from their assigned supplies, while the hammer dwarf practices, when you can pull the hunter off duties, assign them to train in the barracks without bolts with the woodcutter & hammerdwarf.
It'd also be useful for stocking up specific training weapon rooms without pernamently equipping dwarves with wood weapons until unassigned, and just swap them to use any weapon/armor in the confines of their new barracks, rather than plundering your artifacts or weapons supplies.