Kuhl's bit causes damage and shock status to anything that runs into it while it's up. It also gives you a rising defense buff (first 30%, then 60%, then 99%) while it's running. When it's up, you'll gain a buff effect for... I think 25 seconds? Note that when you first pull out your Voltic equipment, you automatically get the buff, so you can save yourself some WB usage by deploying closer to enemy lines than doing it straight off spawn.
The buff basically does two things, other than making most of your attacks look cooler and making your BS always ignited. As Dia noted, the final hit of your normal melee Volt Gauntlet combo will magnetize anything hit, including airs. The other thing is that if you are buffed, your Volt Impact draw attack will now inflict Support Reject and Dash Restrict on things that you punch.
