Most people get either short sword, zanbato, or katana. If you pick katana, you have to acknowledge the fact that you are giving up a significant amount of damage for more attack speed. I really regret buying a Savior Katana rather than finishing Infinite because I can’t find Sensory to save my life. I digress.
Here is my damage with my +11 Savior Katana:
Compare it now with my +11 Savior Zanbato:
Auora has posted a lot of DK data from KDnF in this thread. I condensed it into this Google doc. This is data that is closer to our version and doesn’t account for the recent rebalance of epic sets in KDnF, so keep that in mind. Physical is more powerful for the most part when using sets like Supercontinent, Fiend, and Nagaraja. If you plan on using 7Sins or Gespenst, it would be a better idea to get a short sword.
Attack speed is less of an issue if you have Sensory and an upgraded set. For example, between Sensory and Supercontinent, you are gaining 40% attack speed. Just means you have to pig in hell mode or craft it like me.
TLDR; Get either a zanbato or short sword depending on what end-game set you plan on using. Katana’s are weak but provide a lot of attack speed. From personal experience, I would advise against getting one.