I more or less meant just the hitch part of the assembly. I use "french wrap" as a generic term for that particular kind of hitch wherever it is and whatever the function or the attachment.
Your overall set up I've not seen before though, that's new.
What kind of pulley is that? Is the rod under the wheel load bearing? The new DMM(?) fixed sheave pulleys are, but that looks like an older model. I have an older petzl fixe, and I've often wondered about the load bearing capacity of that portion of the pulley either with a girthed sling or some kind of eye bolt/nut combo through the hole, kind of like adding a becket. The fixe doesn't have a bar like yours, but rather just flat aluminum with a small hole in it.
Also, allthough I haven't tried this in a tree, I think there may be an aluminum alternative to the rope wrench, the Petzl Simple. For those not familiar, it's a bobbin style descender. I learned to use it in the caving world much like a rope wrench in order to descend a weighted rope to reach someone in a small party rescue scenario when down prussiking the line is not an option because of the time involved. Instead of installing it in the typical "S" fashion, you just open it up, put the rope in between the two bobbins and attach the Simple to your harness via a tether. I always backed myself up with a hitch below, at least to start because the weight of the bottom climber makes a difference as to the amount of control you have in the descent.
The angle of the bend in the rope that the Simple and the Rope Wrench introduce may be different, as well as the space in between braking surfaces and the distance of the lever, but the principle is similar. And of course the Simple lacks the "cool" of the RW, but it might work.
