Tetsuya pointed out page 80 of Revised. I'm trying to find the closest equivalents in the original.
Page 37 "Vampires vs Dragons" had...
- Dragons are supernatural beings and creatures of magic, consequently, they can inflict damage to vampires through magic or from a punch.
Actually more than punches and magic. Dragon punch/claw inflicted 2d6 HP, and I believe they did 2d6 MD in the original RMB. Kicks do even more damage, which is interesting because RMB lacked any kind of punch/kick damage distinction for dragons, far as I know.
Both the RMB and WB1 I believe preceded the SNPS damage table in the Conversion Book, so any notes about vampires published in later world books (I think they showed up in South America somewhere?) could be relevant.
Interestingly, this may have been more due to their being CoM than supernatural.
"Other creatures of magic are generally considered to be natural enemies of the vampire"
Although it doesn't specify here that other CoM can damage vampires, it seems more suggested in that direction than the other.
The magic breath also interestingly did 1 consistent amount of damage regardless of what it was, even though damage varied widely for hatchlings in RMB.
Pg 33 had "Magic weapons inflict hit point damage rather than mega-damage when used against vampires" which is interesting when you look at the Zavor in the subsequent conversion book... from page 169
- Magic weapons .. and magic spell attacks .. inflict no damage and will split the zavor into two identical creatures.
- Physical punches, kicks, claws, bites, and breath attacks from creatures of magic, including the za, loogaroo, sphinx, drakin, unicorn and dragons, will also cause the zavor to split into a duplicate every single time he is struck
This seems to put them on a similar par as magic weapons. We also have 5 other creatures on par with dragons for claws and breath attacks having similar mystical effects.
Even though it doesn't state outright that Drakin/Loogaroo/Sphinx/Unicorns/Za can harm vampires, it would be an understandable house rule to a GM with RMB/VK who acquired CB.
Vampires' ability to harm one another (they are supernatural not CoM) does hint in that direction too, but only for vampires... We did have other examples in the book though:
*173: werejaguars "S.D.C. damage from claws or bite inflicts full damage to the hit points of vampires and other werebeasts" I couldn't find anything about vampires being able to hurt werebeasts in return... so I guess vampires would need silver weapons like anybody to fight back. BTW did anyone notice that GARLIC holds werebeasts at bay? Never noticed that before.
Elsewhere we have other clearly supernatural monsters like the Spider Demon Death Weaver, Dybbuk, Incubus/Succubus, Malignous, Mindolar... all do MD and would probably have supernatural PS in their CB update, but none have any notes about harming vampires. Nor did the gods/Demon Lords earlier in the book.
Is the revised VK the first instance of vampires being depowered so that a broader class of creatures (and not just Dragons/Werebeasts) could hurt them in HTH? Did I miss this change in an earlier book?
I'm wondering if maybe C.J. Carella is to blame for this. I think Nightbane/Guardians could hurt vampires with punches when Nightbane RPG came out in 1995, pg 185's modified Limited Invulnerability section carried to Pg 187 which had "The attacks of supernatural beings like Nightbane and Guardians will do direct and full damage to the vampire's hit points." I'm not sure if that means ALL supernatural beings or just ones "like" these two (Athanatos come to mind). Does anyone know any other creatures explicitly mentioned in examples as able to harm vamps?
This note about "attacks of supernatural beings" was not present on page 24's explanation of Limited Invulnerability in the original WB1.