I was initially thinking more along the lines of +1d8 on every odd numbered level or something.
The original plan was fine at higher levels, if you were planning to up the HP of the critters, the damage would be fine, that or making DR more of a factor in combat, as in when it's dictated by a limited set of materials and the damage type.
I'd certainly say that DR should apply to energy and untyped damage, because that's one of the bigger weirdnesses of the system: i'd also say that possibly DR should stack... They've made combat more challenging in my games anyway.
If you used d8s and added in the ability to maximise your blows, possibly by spending a Move or Swift action "adjusting your stance" at a higher level, that would work pretty solidly and you can get +100-ish out of d8s... a bit less, it's true...
The adept abilities are alright. I'd say that they could do with a +5ft Reach ability and an ability that renders terrain in your threatened area Difficult Terrain.
Tactical Expert is a no brainer because it's simply better than all the others. I'd suggest considering carefully whether you want to improve the others or split this in two.
Master abilities: Quick step is potent. This is what i have Mobility do these days. Combat gets...interesting when you throw this in. I like it personally.
Strike with No Thought is certainly unique. Could kick the ass of a lot of combat tactics. I'm reminded of Deathstroke's last appearance in the JLA rogue's gallery.