That link is really convenient for studying the applicable laws — thanks.
I note that they don’t really define “great bodily harm”, or what is reasonable “fear of great bodily harm”, except that if someone breaks into your dwelling you are safe in presuming you’re about to receive great bodily harm.
I suppose juries decide that (or appeals courts with case law as a guide).
You are right that juries decide the meaning of "great bodily harm," but it is generally some irreversible injury. Disfigurement, loss of an eye, loss of use of fingers are great bodily harm. Risk of being cut deep by a knife, even if no permanent loss occurs, is great bodily harm. Same with being exposed to risk/threat of gunshot. There may be some outlier cases where a jury found (risk of) great bodily harm and the appeals court rejected the finding. The jury instructions provide no additional definition.
Cribbed from a post at ar15.com . . .
It usually means there is a large risk of death, disfigurement, or prolonged damage to organs. In FL courts it has also been defined as: great bodily harm ... means "great [harm] as distinguished from slight, trivial, minor or moderate harm and as such, does not include mere bruises as are likely to be inflicted in a simple assault and battery. Coronado v. State, 654 So. 2d 1267, 1270 (Fla. 2d DCA 1995)Here is a slip opinion from the Florida AG, finding it possible for finding a dog to be a deadly weapon. Morris vs. State - 97-2946 - 1st DCA (1998).
On the "safe in presuming" point, there is little safety in a presumption. All a presumption does is shift the burden of production and proof to the state, and we see that the state is willing to take non-credible evidence and otherwise twist facts in order to meet the burden of making an allegation and getting a person to the ordeal of trial.