I have two ideas for a perfect way to pack my TextBlade around, starting with the basic, and then I'll get into the really out of the box.
So, for the basic idea, I think that a small pouch with organizer pockets would be a good choice. It should have enough room for a phone, external battery pack, a few cables, the TextBlade, and maybe a few other odds and ends. It should act as a lapdesk for the TextBlade, as well as a tablet/phone stand. So, for example, you open up the pouch, unfold a desk and put your TextBlade on that, and you have a mobile workstation with your phone, or toss a tablet on there if you want a bigger screen. Something like a Plinth or maybe an Elevated Tablet Stand so it gives that extra little bit of height to the device with the TextBlade underneath.
The pouch, when closed and folded, should be something that can convert between a belt pouch, hanging from a shoulder strap, or attached to a larger bag. I got one of These Little Beauties recently, and it's a very compact pouch with lots of organizer space, and it can be attached to a belt or any bag thanks to the attachment straps on the back. The only thing between that little bag and complete perfection is that it doesn't provide a phone stand or workspace, and it doesn't have its own belt or shoulder strap. Maybe use a holster design of some sort, so that the wearer can put on a belt or shoulder strap, click their desk-in-a-pouch to the holster, and then when they get where they're going, unholster, unfold, and bam, mobile workstation with phone and keyboard.
Now for the crazier, more out of the box idea; way back in the depths of history, I mentioned this idea for a Fast Deploy TextBlade Gauntlet. So, I think something like that would be one of the better ways to carry a TextBlade.
On one arm, a spring-loaded system that deploys into a magnetic desk for the TextBlade. Possibly have it so that the keyboard can always be on that desk, either shut off and fully assembled, or else taken apart just enough that when the desk snaps into place, the TextBlade boots up. (Left and Right blades connected to each other, but broken up from the SpaceBlade until the gauntlet unfolds and flattens out, letting all three blades reconnect). The other alternative would be to make a small slot for the TextBlade to stow into in its stacked configuration, so that you deploy the gauntlet desk, then pull the TextBlade out of its slot (attached by magnets and a small strap to make doubly sure the blades don't fly off your arm), assemble the blades, and snap them to the magnetic desk.
The other hand would be a second gauntlet with a phone holder similar to the tragically ill-fated TUSK: Telephone Utility Support Kit and the rebooted and renamed (and also underfunded on Kickstarter) Wave! Phone Holder. Put a hook or magnet to connect the far end of the pop-out desk to the phone holder on the other side so that the desk is supported at both ends and won't rock around when typing, and now you have your TextBlade and phone always at hand, ready to type anywhere even without a flat surface.
Throw in some other small slots on the gauntlets for other items--charger, cable organizer, key ring, Etc.--make it so the gauntlets can be put on either arm, possibly with a bit of easy disassembly and reassembly, and boom, techno-geek gauntlets worthy of Batman or Iron Man, just more meant for writing down ideas anywhere rather than fighting crime.
Oh and of course, if combined with some Pointing Device that works alongside the TextBlade, this might mean you wouldn't have to touch your phone screen at all--unless you're using an iPhone, since I don't think they have mouse support in iOS. Can't personally attest either way, since I only have the one iDevice (a secondhand iPad Mini 2) that I currently need to run the TextBlade app, and I've never tried using it with a mouse.