The total impact on DPS that SkillSpeed makes on the Warrior is very low. If the necessary SkillSpeed needed for a 9-hit Berserk was much higher, we're talking 500+, then yes, SkillSpeeds weighting will be much higher. The baseline value of SkillSpeed on Warriors is extremely low anyway, so 390 isn't a hard goal to achieve. At 420 SkillSpeed, its weighting is 0.190 with defiance on. I calculated the 0.18x skillspeed with 376 SS. Hardly an impact.

You're much better off just making 390 a secondary requirement, just like accuracy.