The wording of your post seemed to imply that punch was so named by a person, or by people, with knowledge of Sanskrit. This struck me as a bit far-fetched. A quick check at Wikipedia* made everything clear: panch is a Hindi, not a Sanskrit word (in Romanian, it’s cinci --- not sure about Bordurian). Call me nitpicker if you will: I find a difference between what you wrote and what you meant.
Once the nit was picked, I read the rest of the Wikipedia article (anything positive written about ethanolophoric beverages fascinates this old toper), and learned about the delightful (and obviously very ancient, and very pagan) custom of wassailing. I was familiar with the word wassail, and with the ancient toast waes hael and its response, drinc hael --- but nothing did I know of wassailing, as practiced in Southern England. Thanks to you, Zythophile, for that little jewel of trivial but precious knowledge.
I took the Sanskrit origins of “punch” from the OED: I’m sure you and Wikipedia are right about it actually coming into English from Hindi.
If you’re interested in wassailing, you might like my blog post on the subject here.