Concerned about my tokay's tail

[Bogertophis]

Definitely don't do that. The tail honestly looks fine to me. I've seen some geckos regenerate tails that look like that. You can also try GeckosUnlimited.com for more advice, but I think it's pretty normal from what I can see.

a Necrotic tail will become stiff, hard at the end, will shrivel and pretty much die.

I agree, I've seen "dead" tail tips on herps before & that looks to me to be a typical regenerated (live & normal) tail to me too.