To answer the original question:
Attributes, when maxing out, do not compete with Skills (except Bigger and Better vs All-Skilled-UP and gear selection). So no worries there. Put points into other attributes due to equipment requirements (which are rather low) and constitution if you find yourself dying too often, and Wits may give you a bit of an advantage - damage-wise - way later on, but Finesse = main.
When it comes to Skills (i.e. Schools), there ARE competing approaches, that's where style of play comes in:
let's focus on damage:
character is wielding 2 daggers
Dual-Wielding (DW) and Warfare (WF).
Somewhere in the formula the damage will be multiplied by 50% for all normal attacks and weapon based skills while wielding 2 daggers due to DW, but neither Tentacle Lash (TL) nor Mosquito Swarm (MS) will be affected; the damage will be based on level (only matters if you use those Abilities).
Seemingly or according to most people in forums, at the end of the calculation, the damage will be multiplied by 50%... AND (apparently) both TL and MS will be improved (only matters if you use those Abilities).
All due to WF. The catch? you lose 10% dodging.
Why bother mix-matching? TL is Strength based and MS is Intelligence based so bleh! right?
Well, no TL hits HARD on higher levels, independant of weapon (correct me pls), and MS ignores obstacles as long as target is theoretically visible (no path to be blocked!).
A few other physical-damage based Abilities may have similar caveats.
When it comes to Wits and Scoundrel, or better said, critical chance and critical damage the story is quite subtle and not immediately apparent. If you're familiar with diagrams, this is much better than my word-salad:https://goo.gl/images/3vggtg
You will notice optima appear along the general X=Y axis, it's based on another game, but the principle is the same.
So for sure mix your crit chance from gear/talents/Wits with critical damage from gear/Scoundrel/(Two-Handed if you're a warrior).