The Zaros Godsword
The Zaros Godsword is an item obtained as a drop from Nex, the Zarosian General. In order to receive the item as a drop, the player must have the Bandos Kiteshield equipped. The Zaros Godsword has the same stats as the rest of the godswords, and has the same special attack as the Armadyl Godsword.
The Zaros Godsword is exactly the same as an Armadyl Godsword (same stats and special attack). However, you can use the sword with another Godsword to combine them in order to improve its special attack (the new special = AGS special + half of the other godsword's special, see below). The other godsword will be consumed in the process and you cannot reclaim it. Improved Zaros Godswords are also untradeable.
Note: There is no Zaros Godsword (Armadyl), since the plain Zaros Godsword is in essence already an AGS.