Could this count as a pun or is it to far-fetched to not be coincidental?
I don't think it's meant to be a pun. The artist uses the tag "柄ニー" for their images like this one which (as far as my google translate knowledge goes) has nothing to do with the double meaning of vagina. Also, considering the fact that the hilt is the one part of the sword that the sheath doesn't cover, the pun doesn't really hold up in that sense.
本人だけど何か質問ある？ I'm the one who drew this. Any question?
では代理で質問を。 英語で女性器の膣を表す「ヴァギナ」(vagina)は元々「(刀剣の)さや」という意味らしいですが、春待さんの柄ニー絵はそれと関係ありますか？ The English word "vagina" originally means "sheath". Do your hilt-masturbation pictures have anything to do with that?
The short answer is, "They have no special meaning." They are just combinations of object insertions with the tools that have suitable length and shape, and woman-on-top positions.
