Hmmm,......... So if God told the man with one leg to be a football star wouldn't that be unfair or rather expecting something that he knows can't be done? That's how I feel, I don't understand the theology of telling God whether or not I am righteous? God in his power can declare me righteous if he's so wills it, that is not my choice to make but his, after all he is God and not I.
Here's my take on it: YMMV.
The fact that a person with one leg
can fight, persevere, and eventually play football at all is evidence of free-will. The limitation is of course the the Law of Nature as defined by science. So I would agree that free-will is limited. None of us are like the green-lantern(s) who can focus their "will-power" and fly off the ground.
However, looking at it from God's perspective, if that's possible...
Let's say that God's mission for me is to get over my own personal hang-ups, stop being an intense, aggressive, dominant, stereotypical man, and chill for a change. ( All of this still applies for someone who's mission is more Christian, IMO, but this is easier for me to describe. ) I think that God sets the table, ( so to speak, assuming the God exists of course ) and presents me with circumstances which might possibly lead me towards this ultimate goal, which I am calling simply, "to Chill Out". I have the free-will to completely ignore the table that has been set for me. God uses omnipotence to restrict it's own influence into the events of my life excluding those elements which are absolutely essential... in the analogy above, this is the the table which is set, just like for dinner. But God gives me the free-will to to eat or not to eat. To nibble, or to gorge... that's my view of free-will. If I do ignore it, or only nibble, the table is set again in a slightly different manner.
Going back to your example of the amputee from my example is a little awkward though. Because it's insensitive and rude to consider something like a missing limb as some sort of vehicle for growth from the All-mighty. However, I do think that many amputees who have successfully adapted to their situation, may also adopt this point of view. They may see it as there own personal cross to bare. I think both of those attempts at rationalization and understanding are healthy. But that doesn't mean that I would ever suggest it out loud within earshot of anyone who is challenged in a whole host of ways, not just amputees.
So that's my view of free-will. It's limited by the laws of science, and if God exists, then God is able to restrict God's omniscience and omnipotence on a granular level that is very difficult for anyone to imagine.