Just going to toss in my coins about the "melee 2"-system.
The idea behind it is good, but the mechanics behind it aren't the way to go. The first impression people get when seeing the combo list is: "pfff can't be bothered, too much", while in fact it really isn't much. Still, first impressions are strong.
You're on to something, but I'd make the implementation a lot simpler, why not just make some "temporary buff"-gestures instead?
That way people won't have to memorize combinations of buttons to press or new moves, but just a gesture which they might be able to bind to their mouse or other buttons...
Some example 'gestures':
"Killer Strike": Your next 2 strikes will do 50% more damage. Can only be activated once every 15 seconds.
"Warrior's Resolve": Your next 3 melee strikes will generate 7 stamina and health/hit. Can only be activated once every 15 seconds.
"Torcadino Shield Stance": The next 3 incoming attacks will do 50% less damage to you. Can only be activated once every 15 seconds.
"Gorean Parry": You will reflect 150% of the damage of the next incoming melee hit. Can only be activated once every 15 seconds.
And then make it so that they can only use one of them every 15 seconds and only one activated at a time so it'll be a bit more tactical rock-paper-scissors. Give it gorean inspired names and people will be more open for it. You probably should even give it a sound-effect so people can hear and see when others activated a certain effect.
Simpler, cleaner... And you can tweak the numbers over time if one ability is used much more than another etc.
Eventually you could even use gestures like that to buff certain melee weapons:
"Spear Charge": Your next spear-strike restores your stamina and health by 50%.
"Backstab": Your next dagger-strike does 600% more damage.
Just to give some examples on how 'I' would've tried to implement an enjoyable combat experience in the lagfest that is SL.