How does atk speed work with Mercenary crossbow?

It reduces reload time and the time between shots.

If you are using a single-shot skill, you'll notice it mostly in the reload speed, but it will actually shoot faster too, reducing time between button press and projectile leaving the weapon.

With multiple bolt skills, like AP Rounds, the time between shots is reduced. You'll go from rat-tat-tat to ratatatat with some investment.

Two comments. Two opposing answers.

Anything that affects skill speed affects reload speed. Reload speed itself is basically skill speed but only towards the reload animation of crossbow skills, and stacks additively with other sources of skill speed.

And yes, attack speed is very good for Galvanic Shards. You don't need to stack it to the brim, but I recommend using the Stimulants notable (+Crystal Elixir while at it) with Lavianga's Spirits mana flask, which makes the effect of this notable permanent.

Edit: The attack speed suffix you can get on weapons is a local modifier, and effectivelly multiplies other sources of increased skill speed. This and onslaught on kill are both excellent for galvanic shards builds.

i'd cry if we had to stack reload speed on top of attack speed lol

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