Iaito: <a href="https://www.youtube.com/watch?v=r1ROtdYAyps<br" target="_blank" rel="nofollow">https://www.youtube.com/watch...</a> />
Dark Magic: <a href="https://www.youtube.com/watch?v=lvQ9rEakjyA<br" target="_blank" rel="nofollow">https://www.youtube.com/watch...</a> />
Iaito is a really cool weapon, but you won't be able to 1-hand it. Dark magic is viewed as pretty OP. There are some hard counters but very few use them. You've got solid melee potential to fall back on in any case.
There are a few ring substitutions you can do so don't put on the Ring of Favor & Protection/fap ring as soon as you get it. You'll be pretty fragile without it though.
Try out the Bellowing Dragoncrest Ring (+magic damage) or the Lingering Dragoncrest Ring (Crystal Magic Weapon/CMW lasts longer).