Also, some stats do not increase damage linearly. Crit affects both crit rate and damage. At low values of crit, Det and DH provide more benefit, but above a certain point crit takes the lead. Skill speed is even harder to calculate because the damage gain from increased attack rate is non-linear and depends on whether it actually lets you get in more attacks during a fight.

Stat weights are an approximation of nonlinear stats with linear equations. They are never completely accurate, though in the past they were close enough. With how close in value secondary stats are now though, that inaccuracy makes them a bad tool to compare gear.

https://docs.google.com/spreadsheets...it?usp=sharing is more useful for comparing gear. It uses reverse engineered damage formulas to estimate the differences between pieces of gear. It does under-represent skill speed though, because it only calculates its effects on DoT ticks.