Genuinely cool and original idea. doesn't sound too overpowered, although it does kind of seem like a direct upgrade of the trident.
Most people have no idea what an Arquebus is, so i'd rename it a musket. But otherwise, this seems like a balanced alternative to the bow that doesn't completely outshine it, and you made multiple points of why it wouldn't be out of place. Support.
I can see the logic but I don't really see a point. It's such a small change and the window of time the attack animation would have in this suggestion would be so minimal I doubt anyone would dodge it. Plus this would remove the variety of the cooldown and possibly the timing aspect. Spam clicking can still benefit in 1.9, but if you delayed the actual attack, you wouldn't be able to spam click because the animation would keep resetting before the attack hitbox actually goes in. That or it'll just hold your attack and remove the whole timing thing since spam clicking would once again have no consequences (It'll just make combat at a slower, fixed speed, probably promoting spam clicking again)
All in all the cooldown works now because of its variety. Do you wait out the full recharge, or do you attack mid-way? There's reasons to do both and making the actual attack hitbox have a delay would set the cooldown to a fixed minimum, which removes the variety. (And potentially the punishment for spam clicking depending on how it's implemented)
It makes sense, but the current attack can really help you out. The timing change could make things wonky and require very tricky timing, especially when you get swarmed. You could be taking extra hits, just because that attack animation didn't quite reach that "hit part". That's the best I can describe it. I think it'd be better to maybe speed up the animation or something so it looks more sensible.
So eh... maybe like 30% support. To me, it looks like the attacks happen right between when the sword is upright and when the sword is pointing outward.
In nearly every game with some form of melee combat, melee attacks have a swing animation, then hitframes (the moment when the attack actually hits), then they return to the neutral state. Minecraft doesn't do this currently, with attacks hitting exactly the moment you click on the target.
So, the idea is simple - Give all attacks proper swing animation times and hitframes at the END of the attack's animation. This allows being able to actually see attacks coming, and react to them. Additionally, with this change the bizarre attack strength* mechanic would be unnecessary, and the attack speed stat could instead be used to determine the actual amount of time a swing takes before it hits - visible in slower animations for slower weapons. This would also apply to all melee monster attacks.
This would most likely require many new animations, which may or may not fit in to the game's style.
as someone has pointed out, the "cooldown" (it's honestly more like a wierd stamina meter) mechanic does have a form of interesting variety in choosing between DPS and knockback. To compensate for this loss, attacks could be charged as heavy attacks, which do more damage
I am open to constructive criticism and such.
*i still prefer the attack cool-down to pre -1.9 spamfest.