Given the massive pushback against it, allow me to justify/contextualize/defend the Sidearm skill for the Archers.
In the Fire Emblem games, Archers tend to be the most maligned of classes, moreso than Knights and Priests, because their strengths were overwhelmingly outweighed by their faults: they were locked to 2 Range, whereas most enemies were locked at 1. This already poses a problem, because the Archer would only get off one, maybe two shots before it was the enemy's turn, and they would focus melee onto the Archer who can't counter attack, while sending their own ranged guys against your melee troops, also to avoid counter attack. As well, Magic, by virtue of its 1-2 range and the fact that most enemies have mediocre at best resistance, often proved the be the much superior weapon since it allowed them to attack on the enemy's turn. And by virtue of how Archers and Mages tend to be statted in the games, they're both about as squishy in melee, no harm, no foul. And, after FE6, Hit Rates were so naturally high anyway except against, like, Swordmasters, that hyper specialization in Skill was fairly useless, except for games where Snipers got a natural crit rate boost. Not to mention Lances and Axes tended to have a ranged option that served just as well (except in FE11 and 12, where the Javelin and Hand Axe were nerfed to shit) and could still work in melee, and some of the best Bow users tended not to be Archers at all, but those who used Bows as a subweapon. Or Rangers/Nomads, who had bows AND swords AND horses. The one strength Archers had was their weapon was effective against Flyers, but that comes up shockingly rarely, and you still have the range issue.
But Archers are so important to the atmosphere and feel of the setting, they need to be included. So I had to make them more appealing/forgiving to counteract with. For starters was the Defense preferred stat, allowing them to better survive in case the player makes a mistake and gets caught in melee. As far as specialties go, though, the Ballistician specialty was just as situational and restrictive as any of the Terrain based effects. Perhaps even moreso. And there was still the "absolutely helpless during the enemy's turn" issue. So I turned to another strategy game, the Heroes of Might and Magic series.
This is a sprite sheet for one of the archery units in the second game. Because position is so key in that game, protecting archers was often an integral part of any army composition. Still, in case an enemy did cross the entire field to attack the archers, the archers in question could counter-attack in melee, albeit with reduced damage. And that was what I went for with the Sidearm special; give Archers a chance to fight back and contribute during the enemy phase where they really suffer, while still maintaining their identity as ranged fighters. It's also why the Crossbow made a comeback, but is not required to be specialized in.
As for the Effective Damage and the numbers associated, well, that's a lot of numbers to crunch in a vacuum, so, I apologize if I overestimate the effectiveness of some weapons and subcategories, and underestimate others.