OP bases their DRK design too much on the mechanics used by WAR. That's not a path I'd recomend taking because Wrath was designed to work in tandem with Defiance.
On a personal level I'd like to see DRK take up a big sword again like in ages past. XI's iteraction with scythe felt too awkward. MRD's base animations don't really allow for it unless OP intends the job to use a G-axe like MRD and WAR do.
As Kitru said, you'd need to create animations and models for every axe in the game. I don't think thats a good road to take. And I agree that if you wanted a DPS job to branch off a tank class all you'd need to do is set the job crystal to remove the Increased Enmity tags on abilities that have them.
Up the TP cost, remove the DoT. This should be semi-spammable when AoE is called for like Doom Spike.lv 35 Creeping Shadows: Delivers an attack with a potency of 120 on up to 5 targets. Additional effect: DoT effect for 35 potency, lasts 30 seconds. Tp cost of 80
From a really old suggestion I made for DRK:No idea what the rest would be
30 Dark Slash: Sacrifice HP to attack your opponent with a heavy slash, dealing physical damage and additional dark damage.
35 Umbral Symbiosis: Lowers target's Attack and Magic Attack by 3% and increases your Attack and Magic Attack by 3%. Costs 200 MP.
40 Night Slash: Drains TP from up to three targets in front of you. 400 MP cost. 20 second cooldown.
45 Asphyxiate: Interrupts spell-casting. 20-yalm range. 90 second cooldown.
50 Last Resort: Your next three weapon skills consume HP in addition to their normal costs for additional darkness damage.