Low energy weapons are useless in the final game. There are many weapons that become useless as the energy cap increases and I believe this takes away some of the build diversity. So I would suggest the following: Create an energy-based upgrade for armor: Dynamic Armor/Eletric Armor.

https://en.wikipedia.org/wiki/Dynamic_armour

With this change low cost weapon builds could be viable in the final game and there would be more build diversity. Remember that Dynamic Armor is not free, so the cost would be the same as high energy builds.