I was asked to leave this as an Issue, so I'll attempt to make it a list with descriptions of each. Also, I did binge watch Songs of War after the original post, so here we go.
[Warning] Some of these are inspired by features in Spartan Armory and other similar Weapon Mods of the past.

Firstly, Shields:
An upgrade tree for the buckler and an extended one for the shield, possibly having varying effects from speed to explosion resistance and possibly even affecting your overall armor value in one way or another.

Secondly, Weapons in the Songs of War:
Dueling Swords/Rapiers/Cutlass, One-Handed, As seen on Neeka?: Faster than a sword, slower than a dagger, reduced durability compared to the sword.

Glaives/Halberds, Seen on more than a few guards: Two-Handed, As seen similar to Staves: Smaller range and faster than a Lance with sweep. Allows one to remove the sweep from the lance, since it's one-handed, to make it more skill based.

Spears, Similar to Glaives, but no sweep and reduced damage as a One-Handed.

Maces/Morning Stars, Takes longer to sing than a sword or axe, but solid damage, but reduced range. I know you already have maces, but offering some changes, or calling those Clubs at this point, because they look the part of primitive and brutal. Maybe increased Knockback?

Evening Stars, Two-Handed maces with range just above a sword, shorter than a longsword and plenty of damage. Maybe increased Knockback?

War Scythes, Two-Handed with wide sweeps, moderate damage and lowish range. Edgy-Kids and Grim fans rejoice!

Greatsword*, This is half a recommendation as the Longsword fills the role well enough, but 'Beeg Numba Funneh'.

Heavy Crossbow*, It makes sense when you're hunting Ender-Knights and Stone-beings are common place.

Thirdly, Adjustments:
I feel the Two-Handed battle axe is a touch low on damage for it's speed and it doesn't 'Say' it has an extended range.
Too many weapons have a sweep, which is fine overall, it's just odd.
Compared to the base Axe, it seems the Two-Handed Axe is just kind've inferior, which I'm obviously not a fan of. But I could be wrong!

That's the end for now. May post more as I come across them!

On a side note, current weapons may need a greater rebalance as alot of them feel underwhelming at times and the addition of others would create quite the notable imbalance if based off one another. This is just a note for the future.

Cudgel, that's what the current maces could be renamed too. Sorry, just came to me amid a frenzy of bashing with them.

Pretty cool ideas. The idea of this mod is to add only weapons from the series Songs of War and lately I have no plans to add new weapons.