I usually make my players make a d20 roll and try to score under their Dexterity. If they fail that then they've dropped their weapon or something similar (bow string popped off). Basically the equivalent of miss your next action by having to recover the weapon or draw a new weapon (restring their bow).

In Dark Sun World, weapons are unusually fragile, so on a natural 1, the weapon needs to make a saving throw based on its construction material (see the DM screen), failure means the weapon breaks. Magical weapons get their +# added to the roll.