Outside of the clear aesthetic issues with axe dealing blunt damage. Here is a list of balance changes that'd occur from changing warrior to blunt alone;

1. Warrior would not change within itself and would still be taken withing (almost) every party
2. Monk would receive a buff out of not needing to use dragon kick anymore as storms eye applies blunt and then proceeding to use bootshine for all Opo-opo forms, increasing potency of that form by 37.5 (as Dragon kick is used once every 2 Opo forms and bootshine gives 75 more potency as of the guaranteed crit)
3. Dark knight becomes more sought after, as the removal of dragon kick allows delirium to not be overwritten, giving Drk their ONLY utility use again.
4. Ninja gets a slight nerf (although less than the mnk buff) as they'd have to use dancing edge over aeolian edge.

Then giving Drk and Pld a slashing resist down;
1. Ninja nerf removed as they don't have to dancing again.
2. Pld and Drk gain an equal buff for solo and party comp purposes.

In total, the result of this change would be.
None in terms of tank comp, you would still run Pld or Drk and a War (as war still provides path and lots of OT dps). Maybe even making Drk taken even more over Pld
The change would come from the dps comp, likely dropping Drg for Mnk because of the new blunt resist down, even further making Mnk do more dps than Drg, and possibly even making them do more than Drg + the 10% piercing damage on Brd/Mch (from disembowel) + litany bonus. Which, even now, is very close between the two.