That is because your Mana-mana is still scaling well. It’s like how Arde is so good at early levels because you can’t simply get that 153 damage boost on any tick easily from other source.
There is attributes for skills and this boosts even the modifier of skills. Modifiers takes damage from your base. The higher the modifier, the more important increasing base damage becomes.
I’m sure you don’t see it impossible to see 10k damage at end-game right? Heck even some KR players are reaching the damage cap which is 99999. But let’s make the discussion less hardcore so I’ll use 10k as an example. Once you do 10k, the 278 lightning added by Mana-mana is just a mere 2.8% damage increase.
Now let’s go back to Feint+Barrage. Barrage by itself has 500% modifier. With Feint, it becomes double, so that’s 1000%. Eventually, I will reach Lv100 Attribute on my Barrage: Enhance so that doubles the modifier again becoming 2000% as final. Barrage has 3 charges so if all are used, the final total is a 6000% burst.
Just an example, for around Lv170-220, 2H-Bow will have an average 80 base damage advantage over Crossbows, and yes that’s considering the damage variance.
This 80 damage will affect the 6000% modifier of 3x Feint+Barrage. 80*6000% = 4800 damage. That’s not even considering critical yet.
Now, let’s see how Mana-mana will affect Barrage. Good thing Barrage is a multi-hit skill so the additive damage will have better scaling. Barrage’s 15 hits * 278 = 4170 damage. It cannot crit so it stops there.
Even without considering that base attack can crit, 2H-Bow’s base attack advantage already won against Mana-mana’s additive damage if we’re considering everything is at it’s peak (Maxed Attributes).
Now before others say I’m biased on Feint+Barrage. I’ll put another example. Magic Arrow. 25 hits with 100% modifier each.
At max level attribute, it becomes 200% modifier. 200%25 = 5000% total.
Using the sample 80 base attack advantage, 8050 = 4000 damage. If it crits, 6000 damage.
With Mana-mana this time, 25 hits * 278 = 6950 damage.
This time Mana-mana won. But consider that the comparison was just using Lv170-220 2H-Bow vs Crossbow. Now, checkout the difference of Lolopanther Bow and Lolopanther Crossbow. You would finally have your answer.
P.S. Do not use normal attacks as comparison. Normal attacks are just forever 100% modifier.