As far as I can tell, he took the EP values for 2.6 weapons, put them into a calculator or spreadsheet, and adjusted for differing weapon speeds. To quote the wiki,

I don't like the results his adjustment formula derived. Simulation would seem to be a more universal tool.

Edit: I also don't like how he only provides one column of "EJ EP" values. My shaman's gear is entry-level T5. It would be inappropriate for me to use T6 EP values to make gearing choices for upgrading my current gear.

Which was noted to him when he posted that stuff in here a few months ago. Its inaccurate, its misleading, nobody should be basing their gear off of that site. If you have a shaman doing so, they need a swift kick in the ass.

They are for certain, just look at any wws log and take a look at the min/max values.

I thought about Executioner a bit, the reason is quite simple, currently in weo2, executioner is a simple 0.35*840 armorPen (35% uptime), but ArmorPen gets better the more you get and so it's not a really a constant value of armorpen, but a short dps spike. The question is now how can I find a closed form to model this short dps spike.

The idea is simple: Take the dmg increase by 840 ArmorPen in percent, multiple with uptime (35%) and calculate the new armor reduction:

exec_armorpen := 840;
exec_uptime := 0.35;
armor_after := armor_before - exec_armorpen;
dmgincrease := ((armor_before + 10557.5)/(armor_after+10557.5) -1)*exec_uptime+1;
armor_final := solve((armor_before + 10557.5)/(armor_after_new+10557.5) = dmgincrease, armor_after_new);
armor_before := 7700 - 5*520 - 610 - 800;
armor_factor := 1 - (armor_final/(10557.5+armor_final));

the final equation is:
21115.*(20023.+2.*armor_before)/(4.*armor_before^2+81100.*armor_before+410370025.)
Example

armor_before = 7700 - 5*520 - 610 - 800 = 3690
armor_factor = .7572560188
armor_final = 3384.284202
So basically with a fully debuffed bossmob of 7700 armor executioner with 35% uptime is worth a static ~306 ArmorPenetration

The break even with mongoose depends on gear and additional armorPen and MobArmor but should be around 330 ArmorPen

Basically, with an Uptime of 35% it will never properly reach Mongoose with the current gear, an uptime of 40% is required to be beat Mongoose in all areas.
It will beat Mongoose with maximized Sunwell gear on low armor (6200 base armor) mobs though. No luck on high armor boss mobs though. Get's close.

Edit: simplified Equation for effective ArmorPen:

eff_armor_pen := exec_armorpen*exec_uptime*(2.*armor_before+21115.)/(21115.+2.*exec_armorpen*exec_uptime+2.*armor_before-2.*exec_armorpen)

Thank you Yo!.

Maybe I am misunderstanding, but are you saying that if I have over 330 ArP executioner is better then Mongoose?

I have 679 armor penetration and the sim still shows 2xmongoose as about 4dps better.

Just picked up a [Mounting Vengeance], and I ran the sim a few times trying to figure out which weapon would be the superior choice for the main hand in combination with this new toy. What I found out was that it doesn't really matter which weapon I use, I tried [Vanir's Right Fist of Brutality], [Syphon of the Nathrezim] and [Vengeful Gladiator's Cleaver].

Even on different armor bosses, these weapons in combination with the MV would perform approximately the same. Are my values screwed or is this what others are experiencing as well?