Advantages of Oil Quenching：
1. Good elasticity, not easy to bend even in bad cut
2. High-end steel with oil quenching has better sharpness retention |
Advantages of Clay Tempering:
1. Good toughness, not easy to break
2. Better shock absorption
3. Blades are more aesthetically pleasing after polishing
4. More collectible
If you have no experience, please do not DISassemble the sword, because improper force will make the habaki deformation and gap. Copper is very soft, especially red copper. And remember don't close a sword too hard.
The hasaki under the yokotesuji was not entirely sharpened before. Because we make the real geometry yokotesuji. This case is normal amoun the mass-produced sword. It won't happen if it's not real geomitry yokotesuji. Now we have solved this problem. However with the increase in cost.