Originally this was meant to be a thread on abilities for the DDS based on Ascendant Justice, but this can also just be general Covenant ship ideas. So hereafter it'll say 'DDS' but it can really be applied to any vessel.
Maybe a refit DDS (given the Justice was a heavily modified DDS).
Repair and Refit: The DDS's Huragok swarm refits one vessel with improved nanolaminate plating increasing its hull strength. With a high enough cooldown time (or limiting this to capital ships) this can be useful but not ridiculously OP.
Associated Intelligence refit: The DDS-class has a prototype associated intelligence installed aboard allowing it to replicate UNSC AI pathways.
The best way for me to explain the Associated intelligence is that it managed to steal some data from Cortana including ways to make in-atmosphere jumps. So perhaps the DDS (or whatever vessel would get this theoretical ability) would be capable of making pinpoint jumps.
Both of these could obviously use some balance, so play around with the ideas if anyone likes them.