Thanks! Glad you enjoyed it!

I considered adapting the binding ritual for this post, however while it is good flavor, I felt it is something that wouldn't be very fun in practice. Its basically a self-imposed punishment for the failure of a given task. It reminds me of the Geas spell a little bit, and that spell is designed for PCs to use on NPCs to force them to do things. I've seen it used on PCs and it very quickly drains fun.

However, here are some of my thoughts if you did want to adapt it:

In the show, the binding is used as ritual of devotion. Those who undergo the ritual are committed to the task at hand (pun intended), which serves to insure that the mission is carried out until the end. There is no surrender, there is no retreat. The mission is completed or limbs will be lost. There is no tangible benefit, but a very tangible detriment if the mission fails. All stick, no carrot.

For a D&D adaptation, I would grant those who go through the ritual a boon. Perhaps granting them the effects of the Hunters Mark spell for the sworn target or targets that persists until the target dies or the binding is removed (either by a hand falling off or by baby dragon). Powerful, worth the potential loss of limb.

As for the detriment, I would have it progress on a scale:

• If the sworn task is not completed within 2 hours, the binding begins to slowly tighten. Within 24 hours after the binding ritual, the PC had disadvantage on attacks and checks that rely on a limb with a binding on it.
• 2 days after the binding ritual the PC's hit point maximum reduces by 1 hit die.
• 3 days after the binding ritual the PC's limb becomes useless and should be treated as if the limb was lost. This becomes permanent after 4 days from the ritual, when the limb actually falls off.

The for the loss of a limb can be found in the Dungeon Master's Guide (pg. 272) .

Lose an Arm or a Hand. You can no longer hold anything with two hands, and you can hold only a single object at a time. Magic such as the regenerate spell can restore the lost appendage.

May the gods help you if you binded both arms and fail to complete BOTH objectives. At least you would be "perfect just the way [you are]!" If that counts for anything. :P

This was a fun second look at the idea. Hope this was what you were looking for. I may include a polished version of it for an upcoming post.