Argyria

No, It's Not What You'd Imagine
It definitely sounds like an ancient kingdom of the Middle East, where Heptupshet begat Arvashiliad, where they kept a wary eye on both the Roman and Partian empires, and the eating of rock badgers was seen as unclean.

Badger rock.  Close enough

     Actually let us cattle-prod Art awake and tell him to provide the correct article.  Art?  <sound of crackling, smell of burnt flesh>  rock badger, please.

Looking rather smug, frankly

     Hmmm.  I would say "unsporting" rather than "unclean", although your mileage may vary.
     Anyway, enough of what Argyria is not.  What is it?
     A bizarre medical condition, where the subject's skin becomes blue-grey in colour.  Art?

Thus

     The condition is the result of ingestion or inhalation of silver, over a prolonged period in small doses; most of those exhibiting signs have been treating themselves with patent medicines containing silver.  Oddly enough, given that silver is a heavy metal, there are few health consequences of dosing oneself with colloidal coinage.  You might say that the Argyros Touch (after the Greek for 'silver') is a lot less bothersome than the Midas Touch - which is another story.

Hammering Away
Yes, back to the clerihew.  Once again, good taste prevents anything about hammers featuring in the blog title today.  I hope the following are recognisable as Hammer actors, but I'll try to include a photo to enhance your experience.

     

Inrid Pitt

Was quite the hit

Playing the sultry vampire harlot.

She was, definitively, a woman scarlet

     Actually I suppoose if she was one of humanity's leech-like cousins, she'd be more interested in getting the scarlet out of you*.  You might also know her as the undercover British agent in "Where Eagles Dare", where she made getting the red stuff out of enemy Teutons her business.  Conrad unsure if she was happy being typecast as a vamp.

Canines but no cleavage - not an easy photo to find

Michael Ripper

Liked eating kipper.

His being a Cockney, one feels,

Let down the lovers of jellied eels.

     Ah, now we're getting somewhere!  Gently mocking insults.  I've no idea if Michael was a Cockney (checks - he wasn't) - which makes me even more evillll!  I should explain that jellied eels are one of the staples of the Cockney diet.  Conrad, who will eat anything, finds them rather like chicken with lots of bones inserted and then slathered in KY; I shall not be hunting them eagerly in future.
     Art?  Put down that salve and work!

The very definition of a character actor

Ralph Bates

Lacked mates.

So he went to work at Hammer

And dated their ladies of glamour.

     More traducing!  I very much doubt that he lacked friends, and also that he dated the likes of Ingrid or Valerie Leon.  He was a distant relative of Louis Pasteur; I wonder if I can work that into another clerihew**?  Art?  Put down that bandage and work!

Being all arroganty

Meanwhile, Back In Dangerland -
As you know, Conrad has a child-like delight in all things explosive***.  He also has a passing interest in all things poisonous.  So, if he can find a compound that is both, then it's like Christmas and Easter happening simultaneously.
     Hence - Pentaborane.  This is a compound of Boron and Hydrogen, B5H9, and anything containing Boron is quite the opposite of how it sounds.  For a start, it is quite as toxic as nerve gas, meaning one inhalation and - goodbye.  Although you might linger for a day or two.  It will explode on contact with air.  Left to it's own devices, it will decompose into boron compounds that explode if moved or subject to any kind of shock.  It will explode on contact with water.  It will even explode on contact with inert fire-extinguisher compounds, which would make for a challenge if you had a lab accident with this stuff.  Finally, although considered as a potential rocket fuel, if so used then the exhaust fumes would be mild and gentle.  DUH!  Of course they wouldn't, they'd be toxic, too.

Borane rocket fuel in action

     Given what I've just said, anyone taking that picture should be doing it via a telescopic lens from a great way off.  Oh, kidney failure is another symptom of jolly old Pentaborane exposure, so it's a good job you've got two of them.

Finally -
"The spirit of progress (6)" said the Cryptic Crossword clue.  Conrad was stumped, despite going through every Greek and Roman god or godess he could think of.  And what was it?

Grrrrrr!

     Personally I think it should have been Pentaborane.


*  Conrad not at risk; he has nitromethane and lava for blood.
**  Ralph is quaking in heaven ...
***  CAUTION! If your children are like Conrad, lock up all flammable and toxic substances.