The spreadsheet isn't going to be completely accurate, it assumes a perfect rotation and it uses a generic 20% boss armor mitigation. DM buffs aren't in there either but it would be easy to add. It's also using retail formulas for procrates, attack tables etc. Weapon skills are tricky too, it assumes that you're capped at 310 skill however in reality your glancing blows should deal around 95% at 310 and 100% at 315.
2h crit cap 54.4% with 300 weapon skill (100-40 glance-5.6 dodge) so it's not practically reachable. When you dual-wield you have to put up with a 24.6% hit hard cap on top of that.
Regarding Ironfoe I used a 10% proc rate, keep in mind that it procs 2 attacks instead of just one.