How is a weapon's power calculated?

[xXMagnusXx]

I have 2 weapons in my inventory. Both level 13. Except one has 696 power and the other has 961.

Do your stats get factored into that before the number is displayed? Like if I were to respec my stats, would all my weapons power levels change?

[Schalimah]

Yes, your stats are taken into consideration before power level.
It even states a small number under that scaling letter.
That is how much power you gain from that stat.

[Veylox]

Your weapons scale with two of your stats, as indicated for every weapon. The primary stat scales more. Rank S is the highest scaling, then A, B, C...

Weapons also don't have the same base damage to begin with. Some of them are weaker to compensate for really strong perks for example. There's a reason they're two different weapons and not the same one.