Yes, it is generally recommended to wipe off excess oil from a katana after applying it. When oiling a katana, the purpose is to provide a thin protective layer on the blade to help prevent moisture and corrosion. Wiping off excess oil ensures that only a thin and even coating remains, reducing the risk of accumulation and attracting dust or debris.

Here are the general steps to follow when oiling a katana:

1. Clean the Blade: Ensure the blade is clean and free from dust or debris before oiling.
2. Apply Oil: Apply a thin layer of oil to the blade using a clean, lint-free cloth or a soft brush. Use a sparing amount of oil and apply it evenly along the length of the blade.
3. Wipe Off Excess: After applying the oil, gently wipe off any excess oil using a clean cloth or paper towel. The goal is to leave a thin and even coating on the blade, removing any excess that may have accumulated.
4. Handle with Care: Avoid touching the blade with bare hands after oiling to prevent leaving fingerprints or transferring oils from the skin onto the blade.

By wiping off excess oil, you maintain a clean and functional katana while still providing the necessary protection for the blade. It is advisable to consult with a professional swordsmith or experienced practitioner for specific oiling techniques and recommendations based on the type of katana you have and its particular care needs.