When you reach high-end levels, the scaling on gear is disastrously higher, to the point where (roughly speaking) a weapon two levels higher than your own, without modifications, can be close to twice as powerful.
This is not "min/max", the game naturally scales enemy health at a similar rate, and expects your equipment to be up to par.
That's really just an exaggeration right there, level 21 weapon will be noticeably more powerful than level 19 one, but not twice, especially if that 19 in question is Divine and 21 one is epic or something like that.
If you scored some REALLY good level 19 divine weapon it will be just fine and at worst you can pick up replacement gear at trader for pittance anyway, so what's the problem really?
Honestly the end fight is level 20 anyway, if you are talking about level 21 stuff you already over the requirement anyway. It's really a min/max kind of thing and unnecessary at that, really.
