-BAM! I'm Emeril Lagasse.

Doesn't make sense to be on tank. It should be on the turret.

Interlaced with subframe wiring, the Amarr variant utilizes asymmetric power distribution to intelligently reroute power to the suitGÇÖs various subsystems as needed. This improved throughput allows light-class laser weaponry to draw from the suitGÇÖs power reserves to enhance the damage dealt.

Utilizing technologies sourced from across the State, the CommandoGÇÖs subframe is hardwired with custom-built damage modifiers that enhance the output of all light-class railgun weaponry synched with the suitGÇÖs core operating system. This is achieved, in part, by managing the weaponGÇÖs charge efficiency in order to ensure maximum impact of every discharge.

Stripped of all but the most necessary protection, the Minmatar Commando is the fastest, most agile heavy frame on the battlefield. Jury-rigged into the subframe are off-the-shelf damage modifiers able to improve the damage yield of all light-class projectile and explosive weaponry wielded by the user.

Modified to better interface with light-class blaster weaponry, the Gallente CommandoGÇÖs subframe regulates the weaponGÇÖs cyclotron output, improving plasma compression and enhancing the magnetic acceleration of the produced discharge with devastating results.

The weapons and suits aren't separate like modern weaponry and kevlar, they work together, sending data to each other's computers, and regulating power output as necessary.
The above descriptions explain how each Commando's damage amplification works, and I can imagine damage mods behave in a similar fashion.

Notice how damage mods require CPU and PG? Wonder where that's going?
The Commando's damage bonus is probably more efficient since it's custom fitted onto the suit. It's like the difference between duct taping two pieces of metal together, or just having one piece of metal the size of the two.