My suggestion:
Dwarves in Train orders will automatically pick up a training weapon of the same kind as they're currently assigned if available. If not available, they will only perform individual combat drills or observe demonstrations. They will NOT spar or participate. Training weapons will no longer be separately assigned. If Training dwarves leave training orders, they put the training weapon back and grab their assigned weapon.
Background:
Building up my fortress, just got to the point where we need an arsenal dwarf to assign weapons. At first, I was quite confused as to why my dwarves suddenly threw down their swords and refused to pick them back up and were trying to bludgeon kobold thieves to death with their shields. At the moment, they were training shield bashes.
Finally I figured out I needed to assign an arsenal dwarf since my population had just gone over 20. The arsenal dwarf then spent the next 15 minutes dumping rock, doing carpentry, and a few other things before finally getting around to telling the military to pick up their training swords again.
Then a goblin ambush came. I tried to reassign my squad's weapons, but the arsenal dwarf was too busy running away in panic to mention to the military that they should PICK UP REAL SWORDS before going out to fight. Leading to four elite swordsmaster dwarves being completely ineffectual against a goblin horde, and the slaughter of the settlement.
Having to switch between training weapons and real weapons with the arsenal dwarf is silly. Surely dwarves should know to pick up a fake weapon before trying to hack their friend's head off, or not swing it if they can't find one? And to pick up a real weapon when they get real orders? The thought that the dwarf won't grab a real weapon because some noble couldn't stamp a form is... ugh!
And since I can't figure out how to actually tell my dwarves to only do individual drills instead of sparring constantly...