In 90% of space games, small ships die in the first few turns, acting as ablative armour or one-shot weapons platforms. This may or may not reflect reality, but it is poor game design that has small ships simply as weaker versions of large ships, without a defined role. Colonial Battlefleet attempts to shortcut this in its design rules, giving points cuts and bonuses for ships designated "escort" "battle line ship" and whilst this is admirable I think the gameplay itself should do this.
I admire EvE Online, a MMO in which players in tiny frigates could play a useful role (and have a excellent chance of survival) against much bigger ships. The basically made it harder for ships to damage and lock ships smaller then themselves - the bigger the size difference, the harder for the large ship to lock and fire.
I'm striving to do this in Delta Vector with size penalties to hit (which I may make more significant) and the ability to turn unused thrust into 'surviviability'. Currently this has created an anomoly whereas smaller, fast ships can engage larger ships further away, which assumes all size ships have the same computer tracking suites. At least it is different to traditional WW2 combat but it feels a bit weird.
I may go further and add a penalty for each size difference between target and firer; relecting the difficulty in smaller, rapid-fire escort weapons damaging big ships, and slow-firing, slow-traverse big guns tracking smaller ships.
If we can ensure small ships are survivable, and more mobile, then they can be cheap platforms for deploying "special devices" i.e.
This prevents enemy ships engaging jump drives within CQ radius?
Roll a CQ test to fire an emp pulse. Enemy ships in range must pass a CQ test or lose thrust this turn.
Perhaps this also applies to the ship using the EMP.
This degrades enemy weapons, perhaps giving defensive bonuses to friendly ships in CQ range.
Targetting Array/ECCM (Active Sensors)
Cancels out enemy ECM, and if there is no ECM, allows a target to be lit up wiht powerful active sensors, adding +1 to all fire aimed at it...
This enables ships to relay messages between squadrons or drones, effectively extending the range of CQ bonuses and drones control. This also allows friendly ships to jump into areas not inside a gravity well.
This may allow an initative re-roll or similar as the powerful sensors can better predict enemy movements and spot hidden units from double range.
This is a missile-type weapon that detonates where the drift marker was last turn. ALL ships (friendly and hostile) caught in the blast wave suffer damage. Damage is centred on the drift marker and all enemy vessels are automatically attacked. Perhaps it has a 8" radius from the blast zone and does d8 damage to ALL targets in the area -off 1 damage each inch from the blast area.So if it was a d8 roll of 4, a ship 2" away would take only 2 damage... Maybe an EMP blast exists that can shut down all ship weapons if the d8 rolls above the ships' base defence....
Spinal Mount Weapons/Wave Motion Gun
These have a narrow firing arc but perhaps do double damage?