right, here we go. bit disappointing i'm afraid, no specific list for Illyria or Pannonnia, but lots of almost entirely military bits.
My first recommendation (apologies if you have already thought of this as you appear to know some Latin and Roman history) is to get hold of copies of -
Vegetius' 'De Re Militari' (or Epitoma rei militaris); a historian writing in the late 4th century possibly during Theodosius' reign on many topics including the military. very widely known, popularly held to be the basis of most medieval military wisdom, i'm sure you'll have heard of it. copies exist online, check the Wikipedia page for details.

The 'Notitia Dignitatum' is a Roman chancery document up-to-date for about 420AD and contains among the admin detail a list of all the major civil and military dignities (ie offices) including provincials and sometimes even all their senior staff. also give details of shield emblems and military organisational type stuff, and may even tell you which Roman units were stationed in Pannonia.

sources out of the way, here's what i could dig out from the army lists. Dacia has it's own list as follows
Dacians were aggressive raiders and mainly hill and forest tribes, however, they were subdued by and annexed by Trajan by 106AD, although remnant tribes called the Carpi and Carpodacae continued to plague Roman frontiers until around 380AD. they mainly fought like other Germanic tribes in warband shields and spears/javelins type fashion, but also employed javelinmen, skirmishing archers and some cavalry types, rarely as more than about a fifth of their whole force though. their most interesting military feature was the falx, a huge curved blade on a long haft swung two-handed and capable of cutting a man in half, which made quite an impression on Roman observers.
it would be quite feasible to have many eastern mercenary types (Huns, Franks etc) running around in Illyria at this period as it was on the fringe of most migrations west and was even defended by a relic mercenary Roman army under Odovacar in 487AD.
The late Imperial Roman army itself included units specifically called Equites Illyricani, who seem to have been light horse types with javelins and no armour. the army was still based around legionaries optimised for fighting barbarians and cavalry, using longer swords than the gladius, and throwing lighter javelins than pila, also lead weighted throwing darts of similar range to light bows. 10 cohort legions were replaced by smaller 1,200 man units based around the old vexillations (sub-units) of the frontier legions, and would get smaller as time went on. the overall strategy was to field elite regional armies heavily supported by auxiliaries, now called auxilia palatina units, and cavalry vexillations (units). auxilia palatina were similarly armed to the legions with big oval shields, but probably unarmoured whereas the legionaries wore chainmail corselets (long shirts). all foot units probably had supporting archers.
basic field armies had these regular 'palatina' units supported by less well-trained and maintained 'comitatensis' units, and in emergencies by the really dodgy 'pseudocomitatensis' infantry! Roman armies now also fielded some catafractarii and clibanarii (like Kataphracts in MTW). the Romans by 425AD were beginning to field 'foederati', essentially native auxilia units fighting under their own leaders and probably in native styles rather than as trained auxilia. you should definitely check the web pages on the Battle of Frigidus in 394AD as it occurred in Illyria (no doubt you know about it!)

hope this is all useful, if you want more info or clarification on anything do not hesitate to ask!
ave