So, as to wounding, because that's the easy one. If you have the justification to use deadly force on someone you have the justification to use lesser force, including 'shooting to wound'. There is absolutely nothing illegal about that and no law that says you must use only deadly force when justified (although note that shooting someone is deadly force regardless).
It's almost always tactically inadvisable to 'shoot to wound,' but it's not illegal. The only half-arguement you could make is that the prosecutor might try and say that your attempt to wound points towards you not thinking that they were actually a threat; however if we're going in that direction we have to realize that there are cases of prosecutors making the
opposite argument, that shooting someone in the chest without a warning shot was indicative of murderous intent! Ultimately the question is whether the level of force was warranted or not depends on a reasonable fear and state law.
As to 'warning shots' there are 50 different states and I don't know if any of them directly criminalize warning shots- but some of them
specifically ALLOW warning shots! As to Arkansas, there is no mention in the statutes that I can find. The state-mandated carry license course only mentions it as being almost always a bad idea but does not include it in the law section.
Where someone can find themselves in legal peril is if they:
A) Fire a 'warning shot' when they did not have justification for deadly force. The difference between missing and firing a warning shot is such that you may find yourself on trial for attempted murder for your warning shot. The warning shot is not illegal, it's just that you need justification to shoot either way.
B) Fire a warning shot recklessly. If you fire a shot towards someone's house, you are likely guilty of reckless endangerment or whatever the state charge is called. Firing into the air... possibly the same issue although there are instances of people doing just that and
not being charged in Arkansas. But if you fire a bullet into the ground it's not necessarily reckless. Again, it's not that warning shots are illegal- it's the method in which they are done that may lend itself to reckless endangerment. But not necessarily (as long as "A" is not in play).
I'm not interested in arguing whether someone SHOULD fire warning shots or shoot to wound but it's not 'always illegal.'