Slaying Axe or Wo Gun on a DC Titania merge project?

Slaying Axe. Why?

Having Iceberg In One Round Paired Up With DC It's Just The End Of The World

It's obviously dependent on special. If you want a particularly short special, Slaying Axe glimmer is probably the way to go. If you're going for high damage though, glacies slaying axe does more damage than iceberg wo gun if you have more than 33 resistance, which your Titania definately will have. Wo Gun is probably only worth it if you're specifically going moonbow or glimmer with it. In that case, the comparison is as such:

Iceberg Slaying Axe- Does 19 Damage without buffs
Moonbow+Wo Gun- Does more damage if the enemy has 27 or more defence
Glimmer+Wo Gun- Does more damage if your base attack deals 18 or more damage

From there you can decide. If you want to guarantee kills against mages, take glimmer. If you wanna be more well rounded, take moonbow, and if you want something in the middle of those two, take iceberg+slaying axe.

Hope this helps