We can't tell you what might be scaled down, because those technologies don't exist, and likely never will. At least not as personal weapons.
In the world of [insert world name here], lasers became very important, because reasons and we need to scale down lasers as much as possible, while still retaining around 8kW power output for rifles and pistols.
These lasers are mostly free-electron lasers, their structure is 100% match to the IRL versions, we need to scale down these structures to versions, that can be carried around by ordinary humans.
I don't care about financial issues I have infinite cash.
Energy is not a problem.
The weapon should kill the target and only the target.
I have nanobots (with the size of a tardigrade) at my disposal to build things up from the molecular level.
What tricks can I utilize to scale down the size of various components of this laser type, if it's possible?