Update PTS 2.2.2: In the Orsinium PTS, the calculation for Twin blade and blunt and Heavy Weapons are similar thus DW is always better than 2H in Orsinium.
This post is intended for Magicka builds that used dual wielding in 1.6 for increased spell damage. It is essentially an elaboration of one particular point in my post
[PTS 2.1.2 Sorcerer Arithmagic]. In my previous post, I attempted to explain that there is a threshold where two handed results in larger tooltip values than dual wielding even when taking into account the extra set bonus from dual wielding. This was because the passives Heavy Weapons and Twin Blade and Blunt are applied at different points in the calculation. I was not very specific on the threshold but provided equations that would allow one to deduce the threshold. I found that my previous post was not always clearly understood perhaps due to the impenetrability of the equations provided. In this post, I intend to first provide an argument of why two handed is sometimes favoured over dual wielding. I’ll then present the same formula as in my previous post with a bit more explanation for each equation and then give a simplified threshold for determining when to use two handed or dual wielding for maximizing your tooltip damage
At first glance, both Heavy Weapons and Twin Blade and Blunt promise to increase your weapon damage by 5% however this 5% bonus occurs at different points in calculating the tooltip value. For Twin Blade and Blunt only the spell damage component coming from the swords is boosted by 5%. In contrast, the 5% extra damage from Heavy Weapons is only applied to the final tooltip value thus there is no corresponding increase in spell damage. To simplify the argument further, Twin Blade and Blunt gives a flat increase to spell damage while the increase in tooltip damage from Heavy Weapons scales off your Magicka and spell damage from other gear (that is armour/jewellery/Apprentice Mundus).
Thus at some particular point where your Magicka and spell damage from other gear is sufficiently large, using a two handed will give larger tooltip damage values than dual wielding. This is true even when taking into account the extra set bonus from using two weapons instead of one.
Now to put those words into some equations. Let us consider an arbitrary ability and the tooltip value when dual wielding swords (DW) or using a two handed sword (2H)
DW tooltip = a * (Magicka + 10.5 * DW spell damage)
2H tooltip = 1.05* a * (Magicka + 10.5 * 2H spell damage)
where a is the skill coefficient. The spell damage for dual wielding and 2H are clearly different. The spell damage for each equipment is
DW spell damage = Other gear spell damage + (DW damage* 1.2 * 1.05 + 129)*Boost
2H spell damage = Other gear spell damage + 2H damage * Boost
Other gear spell damage refers to spell damage gained from armour, jewellery and the Apprentice Mundus after applying Boost. Boost here means any spell damage boost such as Expert Mage (Sorcerer passive) or more commonly the Major Sorcery buff.
Observed that I have included a 129 in the DW spell damage. This accounts for the extra spell damage coming from an additional weapon and 129 spell damage is the set bonus for a V16 Legendary Torug set. DW damage and 2H damage refers to the value listed on the pertinent weapon when you are hovering over it. In order to determine whether to use DW or 2H we simply need to calculate 2H tooltip – DW tooltip. If it is positive then we go for 2H otherwise we will dual wield. Using some arithmetic
2H Tooltip - DW Tooltip = 0.05 * a * Magicka + 0.525 * a * Other gear spell damage + 11.025 * a * Boost * (2H damage - (DW damage * 1.2 + 129/1.05)
For legendary V16 equipment, 2H damage is 1571 and DW damage is 1335. Using a typical boost value of 20% (so just getting a Major Sorcery buff)
2H Tooltip - DW Tooltip = 0.05 * a * Magicka + 0.525 * a * Other gear spell damage – 2035.53 * a
The skill coefficient, a, is always positive and thus can be safely ignored. The above equations implies that if
0.05 * Magicka + 0.525 * Other gear spell damage > 2035
then use 2H otherwise go for dual wield.
If you didn’t understand that then you can do the following
1) Unequip your weapon and boost yourself appropriately with food and Major Sorcery buff
2) Open your character sheet and record your Magicka and Spell Damage
3) Calculate the following
0.05*Magicka + 0.525*Spell damage
4) If it is higher than 2035 go for a V16 Legendary Greatsword
If not, dual wield V16 swords
If you want an even simpler threshold, here it is
Use a 2H greatsword (and put 2 points into Heavy Weapons) if you have more than 40,000 Magicka.
Final note: This only applied to damaging abilities and does not work for healing abilities with the exception of puncturing sweep since the heal is based on damage done.