Will is still an imprecise term that is not useful for understanding rational decision making.
"he would say that faith in Christ is impossible w/o grace. Faith is a “theological virtue’ in his scheme, and they’re impossible w/o grace."
Nothing is needed beyond what was provided to complete the image as per Gen 1:26-27 in order to make any decision, other than information.
The only consistent and unique meaning for the word faith, in all instances of use is that: faith refers to a belief in what someone says, based predominantly on trust, not on an analysis based on evidence. That definiiton conforms to the use in Mark 5:34, "daughter your faith has healed you". and Mark 6:6, "He was amazed at their lack of faith." Jesus most certainly was not amazed, because he had given no grace to provide for "theological virtue". He was amazed, because they made those decisions on their own while in possesion of sufficient evidence to make the correct decision.
I'm laughing (NOT AT you) because rarely does Aquinas get accused of imprecision!
Check it out: http://www.newadvent.org/summa/3.htm And then root around for will. NOT to persuade but just to see another guy working in his unique way through the questions.