This has been bugging me for quite a while. Where, in any of the books really, is the Tau weaponry? Like, specifically their weapons or armour.

I recall a single enemy entry for Deathwatch that had Fire Warriors, but I don't recall if it fully detailed out their weapons. Any help would be greatly appreciated.

Deathwatch Core and Deathwatch Mark of the Xenos contain a list of Tau weapons and gear, while Deathwatch Rites of Battle has some Tau vehicles.

Also, I (together with my GM) reverse-engineered/home-brewed some stats for Tau battlesuits if you're interested (they only occur in enemy stat blocks in the rules.

That would be greatly appreciated, please and thank you.

I think the only reference to the Tau is in The Soul Reaver, where they have some captured Fire Warriors. Other than that it's only been hinted that the Tau might be somewhere in the Koronus Expanse.

https://docs.google.com/file/d/0B3MNEfkfJJocQVZfNmdJY1hVa3c

All weapons are straight from the books with page ref (except Fusion Blaster, which is reversed engineered from tabletop, where it has the same stats as an Imperial Guard Meltagun, except 50% more range).

Suits are built based on enemy stat blocks. Stealth suit works like Power Armor, Crisis and Broadside work similar to a dreadnaught (except they're still characters, not vehicles).

I pilfered someone else's Tau weaponry stats and equipment one time, and modified it greatly. It's in my link below.

Edit: located in RT, Other Races, RT Tau. Weapons are at the bottom.

If you've used the Deathwatch books, please be sure to take a look at the Deathwatch errata, which erratas almost every weapon in DW and lists the stats for the most common tau weapons. Free for download at the FFG website.

However, Only War returns the Tau Pulse Rifle to its DW pre-errata form (2d10+3 instead of 1d10+12). For some reason.

Maybe because of the different Righteous Fury mechanic. Two dice are more important in that system. Especially if you're not a PC.