Life preserver

But when I gave him every particular that had occurred, he tried to bluster and took down a life-preserver from the wall. I knew my man, however, and I clapped a pistol to his head before he could strike.

(Adventure XI, pg. 160)

“The “life-preserver” consists of a stout piece of cane about a foot long, with a ball of five or six ounces of lead attached firmly to one end by catgut netting, whilst the other end is furnished with a strong leather or catgut loop to go round the wrist and prevent the weapon flying from or being snatched from the hand.

Links:

Image source

Content source

Pistol

An ordinary man could not do it. Now, what do you think would happen if I did break it, Mr. Holder? There would be a noise like a pistol shot.

(Adventure XI, pg 155)

Links:
Image source
History and evolution (timeline)
History and evolution (with pictures)

Jezail

I had remained indoors all day, for the weather had taken a sudden turn to rain, with high autumnal winds, and the Jezail bullet which I had brought back in one of my limbs as a relic of my Afghan campaign throbbed with dull persistence.
(Adventure X, pg. 131)

In the novel, this is the weapon that would have woulded Dr. Watson during his military service in Afghanistan.

Links:

Image source

About the weapon

Rifle

"'Ku Klux Klan. A name derived from the fanciful resemblance to the sound produced by cocking a rifle.
(Adventure V, pg. 69)

Links:
Image source
Content

Revolver

I placed my revolver, cocked, upon the top of the wooden case behind which I crouched. Holmes shot the slide across the front of his lantern and left us in pitch darkness--such an absolute darkness as I have never before experienced.

(Adventure II, pg 31)

Links:
- Image source
- History of the revolver