Vow
With your fingers under an axe, you say a vow. A vow is a sacred promise, so you have to be really serious when you say one. That's why you do it with an axe hovering above your fingers—it's a reminder that if you break this vow your fingers are gonna get chopped off.
Picture the axe hovering above your fingers. Now say the vow. But don't lie. The axe knows when you're lying.
せい
ちか
None
When you finish your vow, you take out your holy blue saber (せい) and cut the axe in half! You know you're never going to break your vow, and if you do, you'll use your own saber to cut off your fingers.
Imagine what it would be like to slice off your own fingers with the saber you've carried for so long. You better not break that vow.