It would reduce the relative effectiveness of that style character and thus make it once more a moot idea. Look at it this way for a sec.
THF gets GB say on 75% of his attacks and DS on 25% of his attacks
The Einhander gets not GB but gets DS on 50% of his attacks
THF do significantly more damage per hit than the Einhander and has similar # or attacks in a combat plus has Glancing Blows... where is the point for the Einhander then?
you may say well just up the DS% for Einhander... well then they invade the space of TWF who would have something like 100% OH and 10% DS. OH has less damage than the Einhander main attacks but OH attacks still proc effects as well.
Instead keep the DS for everyone low and make that a benefit of Einhander and you can balance the styles significantly easier
There are currently few reasons to do the styles other than THF and TWF. I lookat this as an opportunity to expand what DDO has to offer.
Everyone is screamin about nerfs but I think we can use this time to some advantage if we get the thoughts in the right direction.
Glancing Blows: Reduce their frequency but increase the effects Proc... or perhaps remove the Proc completely and just have effects activate if a GB lands. What would be an acceptable % of Attacks producing Glancing Blows if every Glancing Blow had full effect? 75%? 50%? If Glancing Blows did base 10% Physical Damage and the Feats increased that by 10% each would that be accaptable? Would 40% Base Physical Damage plus Effects be too powerful? Would THF be in the top tier? Two Handed Fighting focuses on extra daamge from Glancing Blows.
Off Hand Attacks: Find the right balance. Tempest should be the best at this. It doesn't have to be so much better that it leaves all others wondering why they even bother. Tempest could also include improved damage for off hand attacks. Monks already have full off hand strength why shouldn't tempest get three quarters or so strength off hand. Maybe they have a proc rate 20% higher than the average TWF but also have more straight damage off hande would balance that out. Two Weapon Fighting gains its extra Damage from Off Hand Attacks.
Weapon and Shield: Nearly useless for DPS, only really useful for Intimitanking. Why shouldn't this be a viable style for permanent use. Make a tiered Feat Tree for this Shield Bash, Improved SHield Bash and Greater Shield Bash to have similar Proc effects to how Glancing Blows and Off Hand Attacks are going to be done. Is Shield Style going to be the optimal DPS style? Not a snowballs chance in hell but making it viable stylistically should be a goal. Weapon and Shield gains Extra Damage from Shield Bash Attacks.
Einhander: Single weapon combat. One Handed quick and precise. Same idea. Make it viable and fun. A series of Feat that make it a good DPS option if fully explored. INtroduce the Swashbuckler Class and have it grant said feats. Put something like Single Weapon Defense as an auxilary feat. Einhander would focus on extra main hand attacks granted through a Double Strike mechanic.
Each of these Styles could be affected in similar ways by Movement and Attack Sequence.
perhaps like I'd mentioned Moving reduces the Proc Chance of the individual styles special attacks (GB,OH,DS,SB) by 20% or something and the Spriong attack feat reduces that by 10%.
perhaps Attack sequence reduces or improves those chances -10/0/+10/+20 (or something like that... numbers can be balanced later)
ranged and thrown is another ball of wax and need more solutions to it
The point is that they have an opportunity to make more styles of combat viable and fun if they don't screw it up. More styles of characters and more builds means more characters and more characters means more slots. More slots means more revenue.
just spit ballin on this one
Aesop