One last update on this. I went through every weapon to see exactly how many Hits to Splat each takes, and if it can be reduced.
Here is the data table.
The (A/D) determines the difference between your Attack increases and your opponents Defense increases.
This should fluctuate with minor ability slots. However, I stuck with just Major slots.
A few oddities occur here. For one, there seems to be a damage cap in place. Noticeable on the Jet Squelcher (Probably applies to more weapons if you stack minor abilities as well). This leads into the fact that no weapon can kill quicker with damage ups, only less against armored foes.
Think this really drives the point home. Damage increases are of very little value. Maybe helping in situations where you are trying to push the range of your weapon, or with AoEs.