Modal
A modal weapon can be toggled to deal different types of damage, with the options listed in the weapon’s damage entry. The weapon can deal only one type of damage at a time; changing the weapon’s mode to deal another damage type requires a move action. The weapon category of a modal weapon is based on the first damage type listed. If its second damage type causes it to be considered a different category of weapon when dealing that damage, that category is listed in parentheses. For example, a modal weapon in the flame category that deals 1d6 fire damage or 1d6 cold damage lists “modal (cryo)” to indicate that when it is used to deal cold damage, it is treated as a weapon in the cryo category.
Source
Armory pg. 29