I'll cautiously say that's an interesting idea, but I don't think it's a great one.
Currently weapon specializations already do 10% extra damage a level. 10% accuracy a level is way too much, 2% per level at most.
(2H weapons) Splash damage on normal attacks seems like it could be really overpowered. You'd have to adjust the chance for decapitation - 100% chance is overpowered and make some enemies (like bosses) immune to it.
(1H weapons) -1 AP for normal attacks is HUGE, and would be very overpowered. There's a reason why only daggers cost 2 AP. Retaliation seems like it might be powerful, and it sounds like it's steppng on the toes of Opportunist. Decreased cooldown is also really huge and too powerful, especially stacked with the decreased cooldown for Way of the Warrior.
Keep in mind that those idea would go along with the nerf on strength/dex/int that currently lower cd ap/required as well as a boost on hp of ennemies. We do need something that would make those other talents somewhat useful compared to way of the warrior/other main talent. There's currently almost no reasons to ever take them as long as way of the warrior isn't at 5.
The -1 ap (could be something else) ,decrease cd and aoe is to differentiate the usefulness between two hands and 1 hand. The current problem with the difference between 1 hand and 2 hands or bows and crossbows is that both can use special abilities at the same rate, that's why I think the decrease in cds of skills or ap costs should be linked to bows/one hand instead of str/dex that benefits all type of weapons. The purpose of these changes would be to make 1hand for duels and 2hands for big melees which would seem kinda of natural. If ennemies skills and stats are adjusted to those changes, those talents wouldn't be op but their efficiency would be very different depending on the situation.
Keep in mind that decapitation and lower cds are only available after 15 points in the talent, compared to +4 ap/turns, it's not that strong. While the bosses would be more resistant to it, the usual mobs are currently already killed if you attack them with the 2 hand while they have less than 20% hp. Its use would mainly be on very resistant mobs (which should be most melees).
As for retaliation, it wouldn't do much if there are many ennemies but would only be powerful if you're receiving few but powerful attacks, and that's at the cost of 10 points, more than half of what you receive when you reach lvl10. The bonuses are big, but given how few points you have to use, their cost is also huge.
Of courses those bonuses are only exemples, they could be very different, I just put them here to give an idea of what I meant.
