Mu all the way.
Reasoning is that Katana has more than enough Lethal damage already, and the attack is probably powerful enough that is justifies the redraw every now and again.
Can use it just after a clickyheal or Hasten to minimise the number of redraws, Maelwys (kat/regen) happily does this with Laser Beam eyes + Energy Torrent and until recently he had Air Superiority too.
The -acc from Mu also stacks with +def from Divine Avalanche 
thePhilosopher Martial Arts/Regen/Fire Scrapper
theRegulator Empathy/Energy/Soul Defender
Total Inertia Ice Blast/Kinetics/Psy Corruptor
Total Inferno Ice Blast/Thermal/Leviathan Corruptor
Hey all.
Just looking for some advice and suggestions etc on the following....
I'm a lvl 28 Katana/Regen and I've still not picked from either the Ghost Slaying Axe or the Sands of Mu.
I've tried both powers on test and both have the issue of the draw and redraw of the katana. I don't have a specific attack chain, only that if the power's good to go, I'll hit it!
I'm primarily a character builder and build to suit the history or path of the hero. With either of these powers I can tie something in quite easily but neither leaps out.
So to help my pick, can I gather your thoughts and experiences?
Cheers!
"Like War_Hero said, leave it as it is, it toughens up the softies." - Naz Nomad
Union Heroes
War Borg - Leader of The Paragon Knights
Union Villains
McCabe - Co-leader of The Rogue Knights
Defiant - Supreme Hero