Splinter cloud arrow vs Sickened condition

[Mike Johnson 320]

http://www.d20pfsrd.com/equipment---final/weapons/weapon-descriptions/ammun ition/ammunition-bow-arrow-splintercloud

My GM said that because it's a weapon attack, it gets effected.
I disagreed because it is a burst effect.

[DrowVampyre]

I'm not quite sure what you mean here...obviously the arrow itself isn't subject to the sickened condition (even if it was, it's not making any rolls, so...).

If you're talking about a sickened target being within the burst, though, they would take the penalties, as sickened does penalize saving throws and that has a Reflex save to negate. If you were sickened, it wouldn't really do anything, because you're not actually making any rolls either (it has the Reflex save and affects a burst instead of an attack roll and affecting one target).