your maths is assuming you did the damage that the weapon says it has. You haven't taken into account armour. It depends what mob you tend to grind against and what build you've gone. If you're a dex build I recommend going xbow, if you're a str build I recommend bow. For example, a bow might hit 70 on a mob, while xbow hits 85-90. Just because the bow states it has double the damage doesn't mean you're going to hit double the damage. Also against high def / red mobs, archers with str build will definitely use a bow. If you grind against things your own lvl, I don't really think it matters too much whether you use bow or xbow, so i'd stick with bow for str build, xbow for dex build. TBH it doesn't really make all that much difference until much later, so it's down to what you want to look like and which green / stat bow you find first
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