How about adding a spell to the merchant guild which
would protect their inventories for a short duration.

I think this wouldn't be too abusable and people could
actually get their precious eqs repaired without the
fear of eqs taking damage during the repair.

A skill would be better, some "careful handling" or something, could eat up
200 ep too or so so it couldn't be abused
A spell would be all fine too, but it would make merchants customers wait
longer for those prots, which would rather annoy customers.
Even 5 minutes would be enough duration for this skill, or make it so that it
wears off once you move out of the room, which would work too.
Either that or disable the thing when you're inside pcities/batcity.