black—his gloves of finest mole -- what is mole?

Question

The theme song to the first episode of the television series The Black Adder:

The sound of hoofbeats 'cross the glade,
Good folk, lock up your son and daughter.
Beware the deadly flashing blade
Unless you want to end up shorter.

Black Adder, Black Adder!
He rides a pitch-black steed.
Black Adder, Black Adder!
He's very bad indeed.

Black—his gloves of finest mole.
Black—his codpiece made of metal.
His horse is blacker than a vole;
His pot is blacker than his kettle.

Black Adder, Black Adder!
With many a cunning plan.
Black Adder, Black Adder!
You horrid little man!

There are actually two things that I don't understand in this song.

1: What exactly is mole? A type of material?

2: Beware the deadly flashing blade — Shouldn't it actually be beware of? Because, we don't say beware the dog, but beware of the dog! Right?

Answer 1

A Mole:

Their pelts are regularly used for various purposes and are extremely desirable for their soft texture:

Moles' pelts have a velvety texture not found in surface animals. Surface-dwelling animals tend to have longer fur with a natural tendency for the nap to lie in a particular direction, but to facilitate their burrowing lifestyle, mole pelts are short and very dense and have no particular direction to the nap. This makes it easy for moles to move backwards underground, as their fur is not "brushed the wrong way". The leather is extremely soft and supple.

When the quote says "Gloves of finest mole", it means gloves made out of mole skin.

Beware

These are music lyrics (poetry), first of all, so the rules are more fluid and grammar often is ignored to allow for meter. That being said, beware was often used without "of" in historical texts, like Shakespeare:

This meeting is famously dramatized in William Shakespeare's play Julius Caesar, when Caesar is warned by the soothsayer to "beware the Ides of March."

And in other poetic forms, like the iconic poem "Jabberwocky" by Lewis Carroll:

“Beware the Jabberwock, my son!
    The jaws that bite, the claws that catch!
Beware the Jubjub bird, and shun
    The frumious Bandersnatch!”

Remember that Blackadder is supposed to take place in various historic eras, starting in 1485, so this use is actually quite appropriate for the show.

Answer 2

In this context, "mole" refers to a small animal, the hide of which makes for very soft and supple leather. Mole leather became very popular when the wife of King Edward VII, Alexandra, ordered a fur garment. She did this because moles had become a serious agricultural problem in Scotland, and by ordering the garment, she started a fashion trend favoring mole leather. Thus, mole leather almost overnight became a sensation, and hunters started killing off moles by the hundreds.

As for beware, the use of "of" is optional. It's perfectly alright to say, "Beware the dog!" It's also ok to say, "Beware of the dog." "Beware" is a verb that can be used either transitively or intransitively without significantly changing the meaning.

Answer 3

Before the mole became a protected species (EU), moleskin was used for the lining of winter gloves, furry side in. Mole leather itself is not suitable for the upper material of the glove as it is too fragile. Mole fur was also used to produce a very soft felt for premium top hats, as were rabbit fur for the cheaper version and american beaver fur for everyday purposes.