Ol' Bessie and Der Panzerfaust · 9:21pm
Taken from part of an unpublished story, in the Before Nightfall alternate universe, but these weapons were created before the Point of Divergence and hence exist in the main SWSV worldline as well:
For there had been two sisters, Dawnflower and Duskflower. Two daughters, who were first cousins: Green Apple and Apple Rose. And two husbands of those cousins, Black Smith and Apfel Strudel. And those husband had been fellow agents of the Night Watch -- and boon friends.
And Black Smith had crafted not one, but two, crossbows.
Which one, the repeating arbalest that became affectionately known Ol' Bessie, we are already familiar. That was a general-purpose heavy support weapon, with a three-round magazine and enchanted regenerative action. It shot big bolts, once theoretically capable of killing Dragons.
Its sister was a heavier arbalest. Only a one-shot -- capacity had been sacrificed for throw-weight. But its prodigiously expensive bolts were heavily enchanted life seekers, designed to cleave armor and strike right at the heart of its targets. It could reliably kill a Dragon. And it had been crafted to kill something far greater.
In the funding request, it had been sold to Celestia as a Dragonbane. But Apfel Strudel, who had produced the specs, and it who had a certain Continental ruthlessness in his soul altogether alien to Equestria, had quite another target in mind when he helped Blackie forge its bolts. Not a Dragon, much more powerful than a Dragon, though the legends named her Dragonfriend -- when she wasn't fighting them.
Somepony very close to Celestia. Somepony who Celestia would have died rather than kill. But somepony who was no longer friend to Celestia herself.
Celestia's sister. Luna Selena Nyx, who now styled herself Nightmare Moon.
The heaviest bolts the arbalest could shoot were dedicated Alicorn-Banes.
Strudel's crossbow had a name as well. He had named it "The Armored Fist" in his native Lippanzer-Germane dialect. "Der Panzerfaust."
It was an assassin's weapon, and Alicorns were its intended prey.
I was discussing Alicorn Banes earlier on one of AlaraDRogers' stories. These are an example of Alicorn Banes. Ol'Bessie is marginally capable of such a function, while Der Panzerfaust is actually designed for it as one of its major capabilities.
Since these are crossbows, the shooter would not have to be standing right next to the target for it to work. Since these are not sniper rifles, the shooter would have to be within a few hundred yards maximum. Also, because these are missile weapons, the ammunition would also have to be enchanted.
Der Panzerfaust is a single-shot weapon. Realistically, the shooter would only get one shot comma because an enchanted bolt would be extremely obvious and visible to an Alicorn's senses. She would immediately realize just what sort of a bolt that was, and that she had been its intended target.
The shooter would then have to deal with an angry and perhaps frightened Alicorn within a few hundred yards of himself. This would not be conducive to his long-term battlefield survival.