Arqubex has the highest technical dps potential of any weapon in the game currently. However, it is an arch gun, which has limited mod potential and synergies thanks to [Voidrig] being the only way to use it. Nevertheless, it still functions great at killing enemies.

Since you can’t aim with Arqubex, [Critical Focus] and [Marked Target] are completely useless.

Since this is a pure direct damage build, it will perform less efficiently against very high level enemies with armour. Consider using a viral/corrosive + heat setup if you want to make it more viable in higher levels.
I built radiation just for enemy Necramechs, Murmur units and for Eidolons but you can change the elements as you wish for other enemies.

Side note: Unfortunately, due to the great dps of this weapon, enemies with damage attenuation will become a lot more tankier when hit with the [Arquebex]. Keep that in mind when doing public missions and someone decides to bring out their [Voidrig].