It seems to me that in virus, pistols and smgs/rifles are pretty similiar in function. Both are (in general) relatively long range weapons and both favour continuous instead of burst damage. I’ve been thinking about how the two could be differentiated, while making some sense. And as weapon switch times don’t seem to be very important in Virus, I came up with the idea of dual wielding.
Basically, when using a pistol, the player would have the choice of equipping either the TNT or andrenaline into their other hand. This would allow them to use their selected item by pressing right mouse without taking time to switch to it, and while shooting. To balance it out, pistols would need to have their DPS changed as to be generally lower than smgs/rifles.
The flak cannon could be made an exception to this.