oh i see i have lack of information in my post.
actually i am comparing a shotgun damage with slug shots
black rose[1] - 180atk level 2 weapon
vs
gatekeeperDD[0] - 200atk level 4 weapon
Refine plays a big role here. Base atk variance is also influenced by weapon level, but let's put that aside as it's as much a negative as it is a positive. Also, other gear plays a role here -- but for the following example, let's pretend the character is completely naked other than for the weapon.
A level 2 weapon gets only +3 atk per refine up to +6, and +3~5 after that. If you refined the weapon to +9, you'd get a total of 27~33 atk from refinement.
A level 4 weapon gets +7 atk per refine up to +4, and +7~14 after that. If you refined the weapon to +9, you'd get a total of 63~98 atk from refinement.
So if you plan to only refine them to the safe limit, the level 2 weapon is going to give you more damage if you slot it with a card.
If you plan to refine it beyond the safe limit, the level 4 weapon can surpass whatever bonus the card gives you depending on the refine.
Unfortunately, such examples are rarely useful because the reality is you'll probably have other gear that gives you atk, atk%, ranged atk%, etc that will influence which one is 'better' -- and with ranged weapons specifically, since your status atk matters more.
edit: because of how many variables go into the final damage calculation, it's often better to just use a calc to test damage.
Edited by mildcontempt, 12 October 2017 - 12:50 PM.