Advanced Singularity Thrusters and Research Notes
One day some researchers over in the Helheim system decided to create a ship mounted singularity projector, with the intention of shooting black holes at their enemies. This failed, they couldn't get enough range on it, it wouldn't actually provide enough gravitational pull to form an event horizon, and the gravity pulled on the ship in weird and unpredictable ways, so they gave up on the idea.
Then someone else picked it up and decided to run with it. They realised that by projecting a gravitational well a little ways off of a ship they could make the ship 'fall' in that direction. While the thrust gained in this manner was not exceptional compared to conventional systems, its ability to change the vector of small ships without losing speed was extremely useful to dodging, allowing a ship to throw their entire velocity into a new heading and vector, and improving the maximum distance that they could dodge attacks by in every direction, especially to the rear.
They would essentially slingshot the craft around an arbitrary point in space, allowing it to dodge incoming attacks far more easily. Though it only somewhat increased its rate of travel it had a vast effect on the ship's ability to avoid incoming fire.
By the time the creators of the system were killed research was ongoing in adapting the system to larger craft, but was facing challenges as the creators tried to compensate for the structural strain caused by the uneven pull of gravity on large objects. It was hoped that this system or some variant of it could compensate for the reduced manoeuvrability that immense ships suffer. A Data-Jewel containing the completed design and research was found on Diephobe.
Psi-Throne Mechanicum
A version of a Throne Mechanicum designed to be compatible with psykers, provided by the Eldar. This Throne and its linked psychic circuitry are designed to allow a Knight's pilot to channel their powers though the Titan to greater effect, though only the most powerful of psykers can draw real use of of it.
The Psychic Cannon
The Eldar have provided the design for the Psychic Cannon, a Nova Cannon sized weapon designed for use against Warp Entities that is capable of massed banishment of deamons and significantly disrupting most targets. This weapon is impossibly complex and uses unknown and exotic interactions to work but the Eldar have provided enough schematics to replicate it.
Nanite Repair System
Taken from a massive dark age star ship known as the Scavenger Bot, an ancient ship that at some point was set loose to eternally upgrade itself...well until the Eldar destroyed it. However, its repair system sparked the interest of the Eldar who did it, taking the design as a trophy, but if put to use it would decrease the maintenance of ships as well as providing repairs to them, reducing the number of totally destroyed ships even if it will not be of use in combat directly.