The difference is not negligible. I am playing a NE Rogue in a Semi-Hardcore guild and I am 5% dmg or more behind the other human rogues on damage and that's WITH maladath.
For each + weapon skill you get the following:
Your chance to miss decreases by 0.04%.
Your chance to score a critical hit increases by 0.04%.
Your opponent's chance to block your attack decreases by 0.04%.
Your opponent's chance to parry your attack decreases by 0.04%.
Your opponent's chance to dodge your attack decreases by 0.04%.
The thing is even if you obtain maladath and aquire +9 weaponskill, you will lose the other potensial stats from the OH weapon human uses, i.e ZG OH with faster wep speed for more poison procs and +40 AP, Brutality blade with AP + crit. If you do decide to go daggers, you are required to go Aged cored leather gloves from MC through the entire game(even with dagger from C'thun), and again you will lose alot of stats from better gloves, i.e tier 3 gloves. But as stated in previous comments, it is totally fine going NE/Gnome/Dwarf rogue if you don't care about ranking on Realmplayers or being top dps in your guild.
*Maladath is useless for humans seeing as the total + dps increase from 310-315 is far worse than going a faster OH with better stats.
