Argetlahm (sometimes spelled Airgetlamh or Argetlam depending on the game) is the name of a weapon with different incarnations throughout the Wild Arms series. It seems to borrow its name from a figure in Irish mythology, Nuada Airgetlám.
Wild Arms 2
Wild Arms 3
Jet Enduro's ARM in named Airget-lamh B/V2, which only he is able to use. It is modelled after a machine gun.