I actually liked a single weapon progression. It had some issues, but mainly because of Blizzard's blunders with AP and the Crucible. Get that under control and it's an improvement over the all-or-nothing weapon drops of the past.
I think the system would be even better if you could forge your own weapon at the start of the xpack. Nothing too crazy, but decide if you want an axe or a sword with a few proposed models, or if a caster decide if you want a staff or one-hander+offhand, with the possibility of changing that later on without affecting stats.