For the purposes of plot, all kingdoms aligned or at least neutrally trading with the "X" Empire must from time to time provide liaisons to the empire for special purposes. The duration of liaison service is subject to change, and often does. The emperor's augurs select the liaisons during days long, complicated ceremonies, and the kingdoms are only made aware of the liaison selection when a delegation arrives to retrieve them. No spells of sending, no ravens, just an imperial delegation at the front gate.
You (or your group) receive summons to appear before the emperor of "X" to represent your respective monarchs. The delegation will accompany you on your journey to the empire's capitol, complete with ceremonial armor and weapon kits.
There are appropriate armor kits and weapons for whatever is needed to complete your (or the group's) "theme". Each time there is a summoning, the theme can be different. Use your imagination here. Perhaps the emperor of "X" will decide on elvish craft work on one occasion, and troll-ish on the next, and maybe dryad after that. Retinue members insist that Emperor "X" is absolute in expectations of appearance, so the equipment is more of a uniform than anything else.
The armor and equipment are of exquisite detail. The retinue will explain that their emphasis has been placed on aesthetics, not combat. The equipment will all be almost too beautiful to use for their intended purposes, but fully functional if needed. None of the items provide a statistical bonus.
If detected, all kits will glow with a dim enchantment. If identified properly, it will be discovered that the kits are all enchanted with specialized cantrips/spells of cleaning, purification, and mending. Should anything damage the equipment in any way, the mending spells will be triggered. If soiled or damaged in any way, the cleaning/mending/purifying spells will be triggered. The effect is immediate, and extends to 1 foot from all equipment surfaces, but does not apply to living tissue (creative use of this is encouraged.) If combat occurs while equipped, the triggered spells occur in the following round. There is no limit to how many times the effects can be triggered. In essence, this creates uniforms that are always presentable, regardless of circumstance. This is the limit of the enchantment. Craftsmanship should be considered to meet or exceed masterwork, but in appearance only.
Depending on the circumstances and outcomes of the duration of the liaisons, it may be possible that characters are gifted with their "uniforms", and can keep them when they return from the summons. However, neither the equipment nor the enchantment may be purchased. Emperor "X" had the enchantment researched and created specifically for this purpose, and they do not share the knowledge.
If items were gifted (or retained through other means), and properly researched, reverse engineering is possible, though very difficult.