I discovered something last night. A recruit doesn't have to START with a pick to use it. If the recruit is set to fight unarmed and then has the mining labor enabled, that recruit will go grab a pick as if you'd just assigned him a weapon. What's more, dwarves GAIN MINING EXPERIENCE when fighting with a pick. The dwarf I learned this on died shortly after becoming a dabbling miner, though, considering I'd sent everyone down into an underground pool that still had its denizens.
Today, at the suggestion of the person I first mentioned this to, I loaded DF and Dwarf Therapist, recruited a militarily (and mining-ly) unskilled dwarf and gave her the mining labor, then sent her to kill a groundhog. DT was open so I could look at the experience gains. After the groundhog was dead, she had gained 6 wrestling experience... and 40 mining experience. These events lead me to believe that the mining skill actually DOUBLES as a weapon skill, which would make it the only melee weapon skill that can be trained without risking sparring injuries, not to mention being able to get to legendary in a weapon skill without locking a dwarf into the military. Actually, upon further tests, it seems like having dwarves spar to gain mining skill is ineffective, because they gain wrestling skill MUCH more quickly (62 mining exp to 3,956 wrestling exp, for example).
Still, if mining does double as an ACTUAL weapon skill, think of the possibilities...