I don't think he is saying they wouldn't benefit. All weapon damage would benefit the same yes. But powers that deal damage using Precision benefit from the Precision buff more. You're looking too much into this when it's quite simple. Two powers, Celestial and Fire. Both gain 844 Precision from the weapon buff. Fire from that buff got his weapon damage increased to 161 DPS that's it. Celestial got his weapon damage increased to 161 DPS; PLUS the Celestial's powers got increased by that same 844 Precision buff at the same time. Add on the 45% Annoit increase and it's even further. The issue is not that Fire didn't gain any benefit (he did, the 161 DPS to weapon damage), it's that Celestial gains a much larger benefit from the weapon buff. Since it adds raw Precision onto the character which Precision based powers benefit more off of.