Honestly, the name "Xenarch" is just cool looking so I clicked on it. I read what little is known about the Xenarch and then searched around online for more. I found this...
Xenarch Codex Discussion
People were working on a Codex for the Xenarch! Well, now I was convinced. I got the codex and read the lore created by the 40k fan community and I loved it. Typos, yes. Weird grammar, check. But, the story-line was awesome I was hooked right there. Since, I have a list of brainstorming items that I think will make this fleet unique and fun to play.
Some ideas for the Xenarch Fleet:
-Most fleets are based around the basic weapon batteries, lances, torpedoes, and launch bays. While I am glad that this is streamlined, I do like when fleets modify those weapons or have all new weapons altogether. Eldar, Orks, Necrons, Tyranids; they all have modifications of the basic weapons. I also like when some fleets have a weapon unique to themselves. Take the Star Pulse Generator. No one really has anything like it. When I play with or against Necrons, I have to go into the game knowing they have these weapons and be aware of how they work knowing that they probably have it in place of another weapon or extra points towards other ships. It's part of the Necron style and feel. Also, the Dark Eldar Impalers are something they have unique to themselves and functions similarly to Assault Boats but is still quite different. For the Xenarch, I would like to have a new weapon that only they have. This is difficult because it will be hard to determine a point value for it but I think it can be done.
-We have fleets that are pretty average ranged (IN, The Eldars, Orks, Necrons, Space Marines) and some that have longer range (Chaos, AdMech, Tau). There really aren't any fleets that NEED to be at close (I mean CLOSE) range to function. IN, Orks, and SM, being short ranged and in your face brawlers, still don't have to be THAT close. The IN and some Ork fleets do really well while within 30cm to get the best torpedo shotgun. Getting Huge broadside shots out of their ships, close range is important. I would like the Xenarch to be without pretty much any long ranged weaponry.
-To make up for the lack of long ranged firepower and having very little even average ranged firepower, they will need to be fast. I would like to give them a smaller version of the Necron Inertialess Drives. The Xenarch lore says that they have very high tech "charge cells and capacitors." I think this technology could be applied to their ships' thrusters to prove a good speed and hefty AAF special orders.