It should also be noted that "typical powers" is...well, not all that accurate.  There's definitely squads of machine-winged Legionnaires; there's going to be people with machine powers that make clockwork toys among the Craftsmen, or serve as mechanics for the Merchant Guild.  There are people with the power of healing who serve as researchers; there are people with intellectual gifts that make excellent tacticians or eschew guild membership entirely.  A person is born with their gift, though it requires training to hone.  Guild membership is determined later in life, by one's parents or oneself, and certain requirements must be met before a person is accepted.  Gifts may influence schooling/training which may in turn influence capabilities and guild membership, but by no means are these hard and fast rules.  There's always the person with gift A who just really loves profession Z, and goes in a completely different direction.