How to assign more than one Sign and switch them quickly?
Solution 1:
If you select "Options" on the Launcher and then "Input settings", you get to a screen where you can change the keybindings. There are already predefined keys for each sign on the number keys 5-9. You can either use those or redefine them to more convenient keys.
While you hold Ctrl
to select a sign the time is slowed down considerably, usually that is enough to switch signs in mid-combat. The second slot you see in the bottom left is for throwing daggers, bombs and traps.