Improvised weapon (item)
Improvised weapons include everything from throwing a rock, to wielding a broken glass tankard in a tavern brawl. Any item that that isn't a simple or martial weapon is an improvised weapon, if it can be used as a weapon at all. When an existing weapon is used improperly—such as throwing a sword, stabbing with an arrow, or bashing with a shield—it also counts as an improvised weapon. For most characters using an improvised weapon can deal more damage than an unarmed strike.
Your narrator determines what can be used as a weapon, as well as what damage it deals and any properties it has.
Unskilled Attack. Unless you are somehow skilled with improvised weapons specifically, you don't add your level to any attack roll you make with one.
Damage. A hit with an improvised weapon deals d4 bash damage, unless your narrator determines a more appropriate damage amount or damage type. A wooden stake for example surely can deal stab damage instead of bash.
Thrown. Your narrator determines if an improvised weapon is suitable for throwing. A fist-sized stone, for example. You can throw such an item a distance up to 4 yards as a thrown attack. As a different example, a typical sword is not intended to be a thrown weapon but can surely be thrown as an improvised weapon.