They dont need to explain it. People make a build based on skill usage and availability. when choosing classes you don’t chose it for the weapon, you make your choices depending on what skills you want to be able to have at your disposal.
Gear is simple; use the weapon you need for the skills to be activate-able, and get the best possible one.
When making your build you only look at skills. after you have a class path you want to take, then start looking at what those skill scale off of. For example the cleric heal scales from INT and Max HP more than anything. This is where your stats come from.
In a game like ToS there is no set path, no best option, its really all how you want to play. Feeling like you die too easily? add some CON to your build. Not enough damage? STR or INT. Its all personal experience and no one can tell you what to do, so don’t expect it.