The non-trooper Empire really needs a healer class character. Give the Empire Admiral Piett with a tenacity/health recovery style kit and synergy with Vader and TFP. Afterall, nothing says Empire like "Intensify Forward Fire Power"
Relic Abilities could be used to create the synergy you are describing. Royal Guard could gain a unique that allows him to protect Emperor Palpatine from all single-target attacks, including JKR's mark and Solo's shoot first, as long as Royal Guard is alive. Little things like that to revive one of the best factions in Star Wars lore.