yo dudes i'm the nerdy Yresk here and i've got this hobby about writing my on codexi for sheer amusment.
in the codex i've written i've gone over many times the las family and i've gotten some ideas that might set your mind thinking

Heavy las weapons
heavy las weapons are more or less bulked up las weapons with larger power cells with either a reinforced barrel or multiple barrels
the main advantage of the havy las weapons is that they just can unleash hellish amounts of fire.

H laspistol
Rng 12"
Str 3
AP -
Type Assaut 3

H lasgun
Rng 24"
Str 3
AP -
Type Assault 3

H las repeater
Rng 24"
Str 3
AP-
Type Assault 3/heavy 5

the main idea is no special rules, just a massed volley of shots

Hell weapons
the hell weapon family is basically made to have an armour piercing bonus against tough enemies
in part i had the repeater hellgun much like the H las repeater but also i felt that the weapons did nto do more damage
against armored vehicles even if they punch straigth through power armour. so my simple advise is that when
Hell weapons target armor values they get +2 to the roll due to the blast actually causing more damage. it is not a titanic
devise but it would give a logical bonus to the weapons and make them at least have a chance to take down light vehicles.

lastly the Psylens las family
theese were designed by yours truly to have daemon hunters without the GK running the show. basically they are las weapons set
ona high enrgy setting and all the lenses and internals are sanctified ten times over. fluff wise it causes no more damage to a mortal
but when it hits deamons they do actually feel some pain and it could stagger them and thus let you get in more shots. game wise they have the exact same
stats as normal las weapons but they ignore teh daemonic save much like the GK weapons do.

those are my thoughts. any ideas worth keeping?