Please consider asking your question on an Arch forum (like bbs.archlinux.org), because I'm not sure if these commands apply on Arch.
On eOS I can use
gsettings to change the keybindings via terminal.
get the current binding with your logged in user:
gsettings get org.gnome.settings-daemon.plugins.media-keys terminal
The output is something like:
To change this, you can use:
gsettings set org.gnome.settings-daemon.plugins.media-keys terminal "YOUR-KEYS"
Use the same syntax as in the output earlier and put it in quotation marks. As far as I know, gsettings doesn't check if these keybindings are already in use, so to be sure just try them, before hitting the
After that you can rerun the
get command, to check if it worked or hit the keys you specified.
EDIT: I think, I misunderstood what you want..
In the case you want to change the default terminal-application, the commands would be:
Get the current value and the correct syntax:
gsettings get org.gnome.desktop.default-applications.terminal exec
Set gnome-terminal as default:
gsettings set org.gnome.desktop.default-applications.terminal exec "'gnome-terminal'"