Six Numeri for Honorius

[Robert Vermaat]

I'm tending towards the idea that the Notitia Dignitatum was first drafted in c.AD370, and records the situation during the dual east/west rule of Valentinian I and Valens, with an approximate balance of forces in the two halves of the empire. Northern Britain would be out of date already by that point, still in chaos after the so-called 'barbarian conspiracy'.

I think that's too bold. We can see the changes/updates in the ND because some lists are out of step with others - an original eastrn list from 370 would need to have those 'altered' lists of 394 to show the major changes of, say, 378. And how would Britain be in chaos but, apparently, still not changed by 394?

I would guess that the Octavani were the original mobile detachment of VIII Augusta, perhaps dating back to Constantine or even Diocletian. After the limitanei were withdrawn from the Rhine in c.401 whatever was left of the original legion might have ended up garrisoning Vesontio - or, as you say, the palatine legion might have ended up there. Interesting that the Vesontes ended up in Spain as well - they could have been 're-mobilised' by Constantius III in c.412, or taken across the Pyrennes by Asterius in 419 or the Magister Militum Castinus in 422 - if the Notitia was still being updated that late!

That's possible, but that could also have happened post-350s, after which we see those units incorporated in the field armies.
Summarising Hoffmann and Scharf would take up too much time.. Why can't you read German! 

I still think the later date of 402 is as least as likely as 394, but there's no way of telling... I also suspect Stilicho would have wanted to keep all the field army units he could get his hands on together in one place, to counter the east and/or Alaric - so this mixed-up array of troops could have stayed together for several years anyway.

I think Hoffmann's point is that Stilicho did not keep that army together in Northern Italy, but took action against Alaric with the object of securing power over Arcadius. However, while campaigning with the combined armies he was put in his place by Rufinus who recalled the Eastern army and took them home. 

That makes 394/5 the only time when we find so many units of East and West in that very spot I think?