@Sotanaht can you compare in term of AP?
First, a little about crafting. When crafting a wand, the base material determines both the potential damage output and which spell it gets. Old Wood has the highest damage output (at least out of the ones available at my current level, up to draconic) but sacrifices by only having a basic spell. As far as I know a wand cannot be upgraded once crafted.
Staves may be upgraded with moonstone for damage AND an elemental essence at the same time, allowing a staff to have 2 damage types or an increased single damage type. Not sure how tenebrium enhancing works in the EE yet, if it can be done on top of the elemental enhancement or not, so I won't be testing anything to do with Tenebrium
Now, I have my character otherwise stripped naked with only the base stats required to wield the wands/staves in question, crafted at level 15 with 5 CR. All numbers do however benefit from Leadership rank 1 (+5% damage) as I am unable to remove the trait.
Dual wield old wood wands with no points in wand or dual wield talents hit for 102-168 total combined damage. That's 6 AP to start with. Upgrading the dual wield or wand skill will allow you to increase that, up to 180-300 for 3 AP with 5/5 in both skills. I haven't accounted for possible wand crits. Assuming wand crits even work, as I have yet to notice one in the game, you can simply increase these numbers by whatever % your critical chance is, as the bonus crit damage will always be double.
Obviously investing that heavily in wands is going to come at the cost of not being able to do very much actual spellcasting. Even if you want to rely on wand spells, you need ranks in the associated spell school in order to reduce the AP cost penalties. 5/5 just isn't feasible at this stage of the game.
As far as staves go, crafting with a DIFFERENT element will give you a very slightly higher (single digits) damage than adding the SAME elemental essence, at the cost of having to worry about two separate resistances and immunities. I do not believe Staff of Magus can crit, so investing into 2-handed weapons is pointless unless you plan to melee with the staff.
With 0 skill investments, my Staff of Magus does 124-247 damage at 3 AP with the dual-element staff and 121-245 with the single-element staff. Comparatively, that's nearly 4 times as effective as the non-skilled dual-wand and only about 25% less than the fully-specced 5/5 dual-wand.
So in conclusion, Staves are a better single-shot damage option, whereas dual wands provide double the potential base attribute bonuses and better sustained damage across multiple attacks. I have yet to find any crafting component in the EE that increases mage stats (I've only found tormented souls which are str+dex), so I cannot regain the lost attributes through enhancing the staff. Or in other words, dual wands are nothing but stat-sticks and you probably shouldn't waste points in dual-wielding for a mage.
