As it stands now, living shadow gives you about 7 gcds worth of attacks (lasts for 24 seconds, starts attacking at about 18 seconds). While it's visually satisfying, there is a disconnect in gameplay. Beyond the required blood gauge, there's no mechanic that creates a sense of attachment to the shadow. It's been called a glorified dot and I think that's an accurate assessment.
While I don't think complete control over the shadow is appropriate for its lore (which would be created by gcd mimicry as seen in ninja's bunshin), I think there should be an ogcd button press that issues the command for fray to execute a random gcd/ogcd (fray action). This could be implemented easily by changing the living shadow button into the new ogcd that executes a Fray action. It would have the same cd as dark arts did and be executable after every gcd for a total of 7 hits.
While we have edge/flood of shadow to keep the feeling of dark arts present, I think the extra activity is warranted as blood weapon no longer gives the speed buff and we can consistently double weave. This would also address concerns regarding drk being less fast paced than its previous iterations.
It's arguable that this is just meaningless ogcd spam or that it's too similar to continuation in gunbreaker. Well, continuation happens every 30 seconds whereas fray happens every 120 seconds. It's about 2x the number of ogcds within its available timeframe, but happens 4x less so it has a firm identity that separates it. I also think having a button attached to a fray action will go a long way in not only creating a solid identity for drk, but also in giving living shadow more impact as an action.
Edit: After some more consideration, I do think this implementation is a little weak, especially because it's mindless and doesn't enable decision making. It wouldn't feel right to implement after launch as it'd just be creating more work for the player without a payoff. There's different ways to play off the base idea, though. They could change living shadow into the ogcd that exectutes a fray action, but make it a 5 second or 10 cd (so that you get 4 or 2 off per duration) that ensures that next gcd will be mimicked. Every other gcd by fray would be random (or be part of a set rotation that does the apparent 350 potency "attack" every time it hits, regardless of what the skill visual is). It looked awesome in the job action trailer when bloodspiller came out at the same time on the drk and fray. This would create a situation where you'd be going after high potency weapon skills like bloodspiller or souleater. It also is lore appropriate because it gives the feeling of having some control over your shadow, but not complete control.