This may be common knowledge, but I just realized it and thought I'd share. I had been running my Aloth with Whale of a Wand one handed just for the accuracy bonus (I know it only applies to weapon attacks not spells) when I tried giving him Tuotilo's Palm, the small shield that also counts as an off hand weapon. This means it benefits from two weapon style and weapon and shield style. Normally I don't like offhand weapon shields because in melee they decrease your dps since their damage is so much lower than your main hand weapon would be, but at range you only attack with the wand anyway. Testing dps, he can now kill a dummy rotghast in 1:10 as opposed to 1:30 before, so not only has his dps increased ~20% but he also gains +16 deflection and +16 reflex. Not bad.
Now his autoattack damage is still pretty bad (my watcher can do it in 25 seconds) and he should be casting most of the time anyway, but still you lose nothing since small shields don't have an accuracy penalty. I would even say it helps him weave in autoattacks with his spells since the faster speed means you'll be less likely to be stuck in recovery when you want to cast a spell. I feel like real ranged dps like rangers or rogues would rather be dual wielding or else two-handing something like the red hand, but for casters who only sparingly use their weapon this seems like the best setup.