Slash Attack
gyt, on your suggestion about 2 hit events - sorry if Im not understanding, but won't this just apply to your 2nd weapon as well? I believe I can handle the addition of another hit event on the animation tho.
Mmm, I wasn't clear. This skill has 2 possible animations. One animation fires when wielding one weapon (2-hand or 1-hand, doesn't matter). Then, if you're dual-wielding, it fires a different animation. The dual-wielding animation has 2 HIT points (the other has only 1). With 2 HIT points, it's firing the EVENT_TRIGGER twice, i.e. double damage.
What I suggest is changing one of the HIT points to a HITTWO, which is linked to EVENT_TRIGGER_TWO. Then, we put in an EVENT_TRIGGER_TWO which deals
less than full damage. So, instead of dealing 2xdamage for dual wielding, maybe give it 1.4xdamage.
The EVENT_TRIGGER_TWO will never be called when wielding one weapon because there's no HITTWO point on that animation's timeline.
EVENT_TRIGGER would deal say 86% WDPS, always
EVENT_TRIGGER_TWO would deal say 34% WDPS, but only when dual-wielding.
On the mana cost - can I start it at a higher level (than 5) but still use a graph to increment it?
If you put a value in the MANA_COST field, it overwrites the MANA_GRAPH field, I believe. Or maybe it adds to it. Either way... just use the MANA_GRAPH, then if you want to make it cost more or less, use the MANA_GRAPH_SCALE field.
Shadow Armor
I'm with you gyt on reducing the block so it caps at 18 or so.
I like the idea of greater damage as you level the skill, but I don't think it should be major. Another option is to add something other than damage. knockback? immobilize? DOT?
I'm now thinking that maybe the block bonus on this should be removed altogether and replaced with a flat, level-scaling, bonus to armor. There's too much block going around. Or, it could be something like 0.5% or 0.67% block per level + some bonus flat armor.
Charge Bar
gyt, correct me ifI'm wrong, but wasn't the original idea to grant the effect only when the bar gets full, not while building charge? I remember we computed you'd need to get hit like 25 times before you fill that bar, which is quite a bit of damage to take. So finally getting the effect is probably something you'd really need by that time 
As to what effect is granted, if it's ON/OFF (as I suggest above) I'm fine with either DR or Armor Bonus (maybe because I don't appreciate the finer differences between these). If not, maybe we could consider stuff like %Block? Dodge?
Oh, right now it's a constant bonus that just gets better as the bar builds (so 10% charge = +2%DR right now, 100% charge = +20%DR). It's kinda like the Outlander's charge bar.
I like the constant bonus, but that's just me. I leave the ultimate decision up to you, Phanjam.
Something else to consider so the defensive effect doesn't get overused - could building charge on the "offensive" bar (from landing hits) reduce charge on the defensive bar?
Possible, but would it be desirable? I don't know how this would feel.