First of all, Slayer is the only career without a ranged alternative to kill the enemies. Having a ranged weapon not only allows for safer ways to kill enemies, but allows for niche attacks from a distance that are critical as in attacking a high priority special target who is pouncing your ally or even just attacking an enemy from the right angle. Secondly, not having a ranged weapon means that you are competing with your teammates who do - those teammates who may accidentally attack you with their ranged weaponry and deal damage to you or those teammates who kill the enemies before you are even able to get to them. Finally, with Dual Axes being such a good melee weapon to use in most every situation, the secondary weapon slot for Slayer is often occupied with an inferior melee weapon alternative and, as such, is hardly used or frankly considered to be used. This means that Slayer really uses just one of the weapon slot while the other one is there just for the Power stat advantage to raise your average Hero Power.
I suggest Throwing Axes as the ranged weapon of choice for Slayer as it’s unique to other classes as well as fits with the Slayer personality and playstyle. These throwing axes can be called Tomahawks as well if it fits. It is pictured as a single ax that is thrown with either hand, rotating between left and right. Ammunition is uncapped. The ax will do strong damage to a single target and depleting damage to targets behind the first one hit.
Left Click - At a faster attack speed the ax will be thrown horizontally with a rapid pace. The attack does not pierce, hitting at just where the hitbox is (likely 1-3 enemies).
Right Click - charges the ax, throwing the projectile forward as it’s spinning vertically. Right click again has a vertical spin with the other hand. This is a piercing attack that is a slower attack speed.
I would love to switch back and forth between Dual Axes and Throwing Axes. I think it would make playing Slayer a more enjoyable experience and allow for more skilled players to have better APM.