Honestly my main gripe with the shocktrains is the range of the secondary arcs. The weapon is definitely very powerful when upgraded, but the amount of bonus damage and shield suppression those arcs provide for literally 0 extra effort is pretty insane. You can be quite far from the initial target, and still get blasted when it chains though a bunch of allies. It's brutal when your team is relatively spaced out and behind various different points of cover, but as soon as anyone pokes their head out to do anything, everyone gets zapped by someone they can't even see. It's pretty oppressive, punishes working together as a group, and just feels cheesy. I'd much prefer if either:
a) the arc distance were lowered a decent amount. Have it punish players that are stacked right on top of each other, rather than in the same zip code. This would require the shocktrain user to potential expose themselves to a bunch of enemies at once, adding significant risk to the significant reward.
b) have the arc distance lowered some, remove the ability for it to chain through targets, but have it hit everyone that's within that shorter distance of your initial target. Similar premise to option a; you can do a lot of damage to people clustered behind the same piece of cover / in the same Tyr heal, but you likely have to expose yourself to that whole crew to do so. High risk, high reward.
c) (my favorite) Leave the arc behavior as it is, but make it only capable of arcing to an enemy within a geometric arc 15 degrees or so of the angle it came in from. You'd still be able to blast a large number of targets, but they'd all need to be roughly in line with each other to hit them. I think this is the most interesting solution. The weapon would still have great suppression ability, but would require the user to position themselves such that the enemies are roughly lined up with their shot to get a bunch of hits.