I have to agree with the proposal to remove the requirement (Ymir flesh) all together.

It is supposed to be a tier up from the Stagbreaker, which itself is not boss gated.

The rest of the sledge recipe is fine -just substitute Ymir flesh for something else that is accessible and not boss gated (maybe troll hide?).

It is seldom used as it is so I would think any changes would be with the intent to increase its use as opposed to this change which actually will, I believe, reduce its use even more.