Spears were once used by paladins to train skills. However after the Summer Update 2007 they now do rather high damage and small stones begun taking their place. However they are still used to train by paladins with weaker skills.
After the Summer Update 2007 they automatically return to your hand when it hasn't broken. This is to prevent theft. Tests have shown them to have a break chance of 3%.
After the Christmas 2007 Update, the range of all spears has decreased from 6 sq. to 3 sq. Note that many creatures with distance attacks, such as Minotaur Archers and Beholders try to position themselves 4 sq. away from you which puts them out of range of spears unless you chase after them.