Originally Posted by Darqwood
It's a good idea although I haven't done any experimenting with mount gear. Looking at your research I'd be willing to bet swap_equip is a command to swap two rings/bracelets/etc that are both worn, rather than swapping between gear slot and inventory. If you equipvdl without unequipping first, the worn piece goes to that inventory slot, effectively swapping the pieces.
Unfortunately, using /inventory equipvdl
for a piece of mount tack gets this error message:
You cannot equip a mount-only item. To equip this item on your mount, drag it onto the corresponding unlocked mount equipment slot.
In this case, the desired change is to the stirrups, so I dug out a list of +Shadowharvest
vs. +Rare Harvest Chance (Finder's Stirrups, Plucky Stirrups).
Various attempts using /inventory equip mount_stirrup xxxxxx
result in the message:
Cannot autoequip. No item in slot.
There surely must be some way of addressing that slot?