Note that if you're actually "handicapping" holes, you don't really want to determine the hardest, easiest, etc. holes, you'll want to determine the holes where the poorer player is most likely to need strokes.
For example, in golf most par fives are the lower handicap holes (so players get strokes on them soonest - the #1 handicap hole is first, and so on) because for lower handicap players, they're likely to par or birdie, while poorer golfers are likely to bogey. So those are the holes they "need" strokes on the most.
Par threes (in golf, again) usually are the higher # handicap holes because all players struggle on par threes and average about four - so the 18 handicapper doesn't need strokes from a 9 handicapper on those holes, typically.