So I just experimented a crash: I entered the gnome shop (potions one) and m game froze.
So I closed it thanks to taskbar and when I restarted it and loaded my save, I can't equip any weapons.
If I try to equip a weapon, a "error" sound occur and Connor take the weapon away.
How can I solve this?
EDIT: I solved this bug by downloading a save from Sierraplanet

Note that there are a couple of places that bug similar to this, usually in the shops. Where the game disables your weapons, until you leave the rooms.

One way to get past it is, to walk backwards into the shops. Also try lowering and turning off the graphics options in the menus..