Excavator specializes in using Dual Pistols. Along with unique weaponry (based into skills) such as poison bombs, mines, and dynamite.
Excavator is classified as an AoE class, in that all of the main skills, effect a certain area causing either damage, or debuff.
As with most classes, equipment with HP or MP unseal bonuses are good, so keep unsealing equipment until you get nice bonuses. Your boots are the only type of armour that can get an avoidance bonus, which is vital for an AoE exca. Once you get to level 45+, you should aim to always get avoid bonuses on your boots (as well as the default avoid bonus on second class armour boots). The more avoidance you have, the less hits you'll take and the better you'll be able to AoE.