The Black Arrow eWallet will run signed Trezor firmware, and displays on the screen that it is Trezor firmware:
Bootloader appears to check and affirm Trezor-signed firmware images. The button mappings are correct.
This works, but is probably a terrible idea.
The eWallet does run unsigned firmwares, displaying the standard warning before continuing.
Remember, Black Arrow has NOT yet released source code for either their firmware or their bootloader. It appears that the eWallet can confirm that signed Trezor firmwares are running in a trustworthy fashion, but without source andor bootloader reversing, we cannot be sure. Black Arrow claims to be open source. This is currently a lie.
Whether or not you agree with their business plan, BWallet has never misrepresented their product. (As for as I know)