A Throwing Pick is a type of weapon that is small, easily concealed, and used for damaging small animals or objects. Due to its size, it can only slightly damage players, but can kill smaller animals with a single strike. Some types of it are also known to have attribute called "Continuous Piercing Damage over Time (DoT)", which will inflict damage per five seconds until it is taken out.
Chronology
Sword Art Online
A Murder Case in the Area (Aincrad 57th floor, April 2024)
In the anime it is used against the escaping phantom avenger in the Murder in the Area Arc as he flees on the roof. In the light novel, Kirito also uses this pick to experimenting with "Continuous Piercing DoT" while investigating with the inside-area PK Case.
Year II
Kirito uses this weapon to kill the Ragout Rabbit as he doesn't believe that he'll be able to catch the rabbit with sword.
Kirito throws one at Kuradeel's face to delay him from killing him when he was paralyzed, but due to the paralyze status, his aim was off and hits Kuradeel's arm instead.