That’s the legendary/mythical heat hook which is an awesome item.
FLAMING GRAPPLING HOOK— (17) 111-145 ExDmg, 39HeatDmg, 1Use, (0/31 Cost)
Overall I think your build looks good. The modules will probably change as you play it, I potentially see you using less energy and more heat modules, considering that your desolation and your shotgun, plus charge and hook, are all energy free. You could be drained and still kill an energy mech pretty easily.
Hitpoints will be solid at 1839.
Drone Nemo would probably be a little better but I am not sure about that.