This effect is a curse rather than an advantage.
On a successful hit, if the kickback triggers (% odds), will automatically deal to you as much damage as the rated percent amount of the total damage caused to the enemy.
Example:
Your mech is a Namtar level 32 (with Kickback 17% odds 50% dam by its build). On a successful shot for 50 damage, it triggers the kickback (that was a 17% chance here) dealing 25 damage to itself (50% of your 50 damage).
Notes:
1. The kickback damage isn't substracted from the damage dealt to the enemy.
This effect is generally designed to balance overpower, but this is certainly debatable as there are better effects without penalty.
2. When trying to pilot a mech of high tonnage without the skill "heavy" high enough, the mech will suffer dysfunctions caused by the poor training of the pilot, suffering frequent Kickback that will often leave that mech out of combat.
Tips:
Get rid on any kickback if posible, as that effect will only contribute to suicide your own units.
Namtars are said to cause disfuctions... skip them. Weaponry with Kickback can turn the edge of battle against yourself... Replace them.
There is only a situation in which you may use Kickback in special mech builds to cause a Nuke that may distroy both, your enemy and your exploding mech. Interesting trade off when the enemy mech was so strong. [Check the Engine: Handheld Nuke]. basically you trade a so high chance to deal huge damage, with a certain sacrifice of your own mech.