TL:DR at bottom
The increased attack range is listed on the weapon itself (10 to 1h spears 5).
The modifier itself is hidden and on both 2h Sword and Spear (it’s possibly Muskateer and 2h Bow also have this bonus).
The 2h Sword bonus is listed in the damage formula thread, but it hasn’t been updated and doesn’t include the Spear (which you can confirm for yourself, but I confirmed it last night). This is a simple check of your minimum-max value - Enemy Def and recording the expected damage vs the result (you will deal more then your min physical attack-enemy def and max physical attack - enemy def, as a result of the modifier by 10%). The Modifier applies after defense calculations.
Going forward, going by their Max attack is inaccurate as well go by their average.
Brandish has an average damage of 187.5 + 24 str for 211.5
Catacombs PIke has an average damage of 358. Crit rates value depends on enemy crit resist. If your Crit is above their crit resist the 23 crit rate (at level 170 specifically) is a 2.8% average damage increase that decreases with every level you gain.
211.5 + 322 (large) is 533.5
358 + 188 = 546. So on the surface the 2h Spear is slightly more potent on Large enemies on average, prior to considering off-hand stats or the 2h spears modifier.
Arde Dagger is 153 Attack. The 2H spear adds equivalent (via the modifier) when your effective attack (Physical attack + Skill damage - Enemy defence) is equal to 1053 or greater.
Lets assume (just for arguments sake) you have both weapons Exactly at level 170, still rank 5, in a Full STR build with 3 stat points gotten from Crystal mines, Tenet, Watchamacallit forest, Mage Tower, Sanctuary, and Benei reinforest, + 6 stat points from statues. That’s 24 Extra stat points for that investment.
That’s 571 Physical attack add it to your average weapon damage.
211.5 + 571 = 782.5
358 + 571 = 929.
We’ll use Saiuluvs as an enemy since they’re cloth (neutral damage) and 187 Def.
595.5 For 1h Spear
742 For 2H spear.
You’re already at a 147 Damage difference Btw in favor of 2h Spear.
Sailuvs are medium so add 49 (from Brandish)
and its 644.5 + 153 from arde = 797.5, Karaches 61 would put it to 858.5
vs
10% Modifier for 2h Spear brings its output to 816.2
2h Spear’s advantage in this situation changes whether you have Arde’s Kar, or if you’re using a shield instead of a dagger, and 2h Spear is pretty much consistently better on small targets
Now if the Saiuluv was Large instead.
The 1h Spear + arde would do 1070.5
2h Spear would do 1004.2
Brandish does have the benefit of having 1 more AoE ratio
Now Skills matter because as you probably noticed, the 2H spear has a higher output after defense is calculated so larger skill damage can tip this in 2h spears favor because of it’s modifier and any the skill may have.
I think an easier way to simplify this is just take 10% of your average effective attack. If this bonus is greater then Arde Dagger then take the difference between that and the +damage to medium/large types and compare.
TL:DR.
2h weapons (catacombs) are going to do more damage with the same skills used unless you’ve got Low STR assuming I haven’t forgotten anything in my calcs. 1h Spears will also often be more effective against Large enemies. The lower your STR the more significance Arde Dagger has.
