Guild Wars 2

You could swap between 3 weapon sets instead of 2?

Exotics would shoot up in price.
Engineers would laugh. Or cry. One of the two.
The UI would have to change.
Weapon sets with overlapping skills would remain on cooldown after use.
Players would cheer about flexibility.
Players would kitten about everything else.

Adding to Rauderi’s ones.

Combat becomes harder to balance. We all know ANet already struggles to balance the combat, let alone traits, let alone weapon skills.

Warriors could bring more CC without sacrificing engage/disengage abilities.

Ele/engi would be left behind, or have even more crazy spam rotations if given a second set.

Thief even harder to kill. So many perma stealths and perma evades and shadow steps on demand.

Guardians can bring mobility along with their high survivability weapons.

I see nothing but pain and tears, if weapon sets are increased.