How would is Implement Throwing swords/ melee ranged weapons?

Sure, give every unit built-in DC just like the dragons, that sure won't be an issue.

Notice how in most recent fire emblem games, the javelins either had very low MT or just straight up couldn't let you perform follow-ups at all?
I wasn't surprised that they didn't implement these weapons from the start.

For the swords we already have weapons with DC built into them so the concept would be the same, maybe just change the animation. Longbows I doubt will ever make an appearance or any weapon with a range greater than 2 for that matter. Battles are on such a small scale that increasing your effective range by 1 would be absolutely busted. Its not like in main series games where you have plenty of room to run or spread out, when the grid is as small as it is in FEH you'll never escape unless you're a cavalier

Things like these should be left alone. What makes FEH great is its simplicity in combat mechanics. The main selling point of the game is the fact that you can use units from different FE titles. I think Distant Counter and Close Counter skills are enough for this game, as it gives units a chance to counterattack due to range limitations. I mean we already have dazzling effect and sweep skills if you're really bent on preventing counterattacks. But for melee units to have access to weapons that allow them to hit at range on initiation undermines the use of tome and bow units. Likewise, ranged units that can hit at close range on initiation undermines their function to hit at long range. They might as well be melee units and that's an awkward concept for units that are meant to hit from afar.