Hard to tell. He was pretty adamant about wanting hardness. Strength is an entirely different thing.
Lots of hard woods (not to be confused with hardwoods). I was going to refer to the Janka scale comparisons out there but I couldn’t address the other part of the question - the hardest that the GF can cut. I know there are some folks who have done experiments with stuff like ironwood but I don’t have any details.
But if he really wants what he’s been asking for, here’s the Janka scale info anyway.
