The Plot

Ward Hill Lamon here.
Formerly employed in the law firm of Lincoln and Lamon of Danville, Illinois he was more than Lincoln's law partner, he was his friend, bodyguard and biographer as well.
He's played by some guy named Leo Coco in a recent flick called "Saving Lincoln" which concerns a never-quite-confirmed-or-dismissed alleged attempt on the president (elect)'s life which was supposed to occur as he was en route to his inauguration.
The proto-security contractor Alan Pinckerton had been commissioned by the railroads to provide security for Lincoln's train and his moles ultimately reported that there was a plan afoot.
One of his seventy scheduled stops was in Baltimore where, as the President's train was in the station and he was on the platform engaging in retail politics, a sort of stabby flash-mob would appear and stab honest Abe. At least one of them would be close enough presumably.
This was a big problem for the folks orchestrating this thing. Not that Lincoln will be killed. That's not going to happen now that they know about it. The big worry is how they're going to spin it.
The gentleman pictured above, Mr. Lamon said he'd supply Abe with a Bowie knife and a revolver for the stay in Baltimore but Pinkerton said: "...would not for the world have it said that Mr. Lincoln had to enter the National Capitol armed."

"Baltimoreans Pissed at Lincoln No-Show!"
by Thomas Nast

It was set up so Lincoln would arrive in Baltimore the night before his expected arrival, then his rail carriage would be surreptitiously towed through the city by horses as Baltimore didn't allow rail travel at night.
Mama Lincoln and the kids came the next day as scheduled but they got off the train a couple of blocks from the station so the good folk of Baltimore never got to see them either.
The punditry had a field day.
Lincoln was portrayed as having sneaked into Washington in disguise - in a cattle car in this cartoon, one of the best of the lot of them.
One Joe Howard Jr. a sleazeball writer for the new York Times claimed that Lincoln had worn "...a Scotch cap and long military cloak"; said reporting having been based on... nuthin'.
Hence the get-up we see in the cartoon where the cap is rendered as a Glengarry bonnet.
It's priceless. Abe looks terrified. Even the cat's pissed at him and the car has a capacity of "000" (?)
The entire crisis came to nothing and there is some doubt as to whether there even was a plot to begin with.
Lincoln felt like an idiot and regretted slipping through the city and his buddy Ward Hill Lamon later said that the Prez had never been in any danger whatsoever.
On the case, Lamon was.
When Lincoln had been elected, Lamon had been hoping for some sort of diplomatic post but, having been brought along on this junket, he took it upon himself to be a protector to the Big Fella from this time forth.
He patrolled the grounds of the White House every night and one night in 1865, having apprehended a miscreant armed with two knives and two pistols, he curled up on the floor in front of the boss' bedroom for the rest of the night.
He was with Lincoln during his ignominious trip through sleeping Baltimore and here's were we segue into my massive product roll-out and the further proof - if needed - of my shameless, if incompetent opportunism.

Pictured to the left: The first of only three listings for "brass knuckles" in the Library of Congress.
Accompanying text:
"Brass knuckles carried by Lincoln's bodyguards during his train ride through Baltimore.] Artifact in the museum collection, National Park Service, Ford's Theatre National Historic Site, Washington, D.C."
So it's unclear. They could have been old Lamon's knucks or they could have belonged to one of the Pinkertons.
I'm going with Lamon and there's a tie-in to the great Emancipator regardless.
 

A quick note about the photo of Lamon: It looks to me like he's fully strapped.

Or it could be his lunch.