The concept of Damage Per Second as a way to compare weapons, classes, and sets abstracts away from several aspects of gameplay. As a result, it can be misleading. A weapon/setup with lower DPS may be more effective in various situations.
One aspect of gameplay not captured by DPS is the amount of time for which a weapon is fired. DPS is actually the limit of damage/time as time approaches infinity. If we start timing at the moment the first shot hits a target, then real damage/time begins at infinity and remains much higher than DPS over the first few shots of a weapon. This is one reason why items with high damage and slow rate of fire are more powerful than a simple DPS calculation would suggests. (The other reason is that they are less impacted by enemy DEF.)
Below are graphs of average DPS over time comparing Acclaim and Ancient Stone Sword on maxed Knight with tops, and comparing Doom Bow and Leaf Bow on Archer with tops, assuming enemy DEF is 20 . The graphs show that the real average DPS of these high-Dmg-low-RoF weapons is greater for the first 2-3 shots.