Good post, thanks for checking the actual numbers. It seems however you have a mistake somewhere when you compare full spec wands with staff, since that's not 8% less, it's quite a bit more. Maybe you compared 5DW/0wand damage or something, which sounds it'd something like that. It's about 25% less with the numbers you provided.
I also kinda disagree with your conclusion, dual wands are worth it if your main intent is doing damage with your mage. Truth is, lategame, most spells do garbage damage. You can still do ok using poison/fire combos but only against mobs that are not resistant to fire or immune to either, and with the nerf to the cooldown reduction from high int, you can't spam nearly as well as you used to either, and that's not counting all the master spells that can now only be cast once per fight.
Wands can crit(and can come with 5%crit each, which iirc stacks globally rather than being per wand), always hit and have incredible damage efficiency. A single shot of wands with the numbers you provided is several times better than most spells unless you're hitting large amount of targets, when comparing equal AP costs(most high end spells cost 7 or more AP, meaning you get 2 swings). It's also pretty much superior to every single option but Death Punch for single target damage, which is relevant when trying to take down specific targets quickly(like bosses, or aura monsters in tactician and such).
Now when comparing wands to staves, the main argument imo is staves limitation to 1 shot per turn, which is a huge downside. At 3AP, it's not a good way to burn your excess AP for damage. Quite often near the end of a fight, I'm out of offensive spells and I still get 8AP a turn. There's no need to debuff the last 1-2 half health mobs, and being able to spam wands makes the fights go faster. That's when not using wands as a main source of damage(I have 0/0). That's the main reason I don't equip staves, too often I end up burning the last few mobs with wands and staves would force me to go into melee, which could turn wrong for no reason so I'd just pass instead, wasting time.
Also of note, it only takes 2pts in dual wield to reduce the AP cost to 4. Those points I think are way more cost efficient than the ones after and it'd probably be worth comparing 2pt DW/1pt wand, which is only 4 ability points, versus staves. I'd reckon with the additional int, it'd be quite a decent investment for ability points.
