I built a software model to optimize efficiency of stat allocation .  These are its limitations:

The model ignores these game elements:

  1. When player HP drops below 25%, the multistrike and crit percentages increase.
  2. Other items that affect crit
  3. Area bonuses, like +crit% and +multistrike

The model computes many things precisely, but makes a few changes to simplify the math:

  1. It ignores rounding.
  2. It approximates the sum of many uniformly distributed random numbers by using a normal distribution with appropriate mean/variance, and truncated based on the lowest and highest possible values of the random number.
  3. When multiplying random variables, I use numerical methods to get approximations that have roughly 2% error in variance and 10^-6 error in mean