I don't swap weapons back and forth, honestly. I train groups, and the trainees get silver weapons (hopefully lower quality) until I no longer want them to spar. I try to upgrade the various squads' armor as it becomes available. I play the game vanilla, so YMMV.
This is pretty much what I want to do, but how do you get them to switch from silver weapons to iron, steel?
O! Sorry, I misunderstood you.
I try to at least have a set of leather+chain, giving them time to grab their under-armor first. and a shield for each recruit in a squad I'm raising (I typically go with pairs, rather than larger squads). If possible, I go chain > plate directly, instead (Heavy?
Deal with it, Edem).
Turn 'em loose to train wrestling/etc. as long as I feel. I usually only bother up to the range of proficient-talented for melee fighters. I know a lot of people will train 'em all up to legendary.
Weapons are sorted into separate stockpile rooms with doors based on composition (intended-for-training and post-training being my categories). When I decide a "class" of recruits is ready for weapons training, I put 'em on duty and station them in the former of the two stockpile-rooms. I lock the door, and tell them to use whichever weapon. They stay there till they get the idea.
When training is done(here's when I train them until they're a ledgendary foo), I order the squads back to the to Trainee Storage and disarm them (command them to fight unarmed). Then I send them over to Duty-Issue Storage and lock 'em in till they're equipped.
If I have to, at some point, get something out of a warrior's hands, I order them to have neither shield nor weapon, and order the offending item(s) dumped.
Of course, I think that a lot of this will be obsolete in the coming version.