By the time of the late 4th to the middle of the Fifth, Rome's Armies had to depend on it Aliies's (the Goths) to defend Gaul.
And so they did under Flavius Aetius.
I doubt that Aetius was a true Flavian, but that is not Germane here.
by 450 the 'arm of decision' was now partially the heavy Gothic Cavalry and the Heavy Roman Infantry.
The Arms training. discipline , armor, and dress would not being really be recognizable to those of us used to the appearance of the Imperial Infantryman of prior Centuries.
The Legionary carried a 6-8' spear, a round shield, a long sword called the 'spatha' and darts ('plombata') .
Off duty they trained also with the bow, and we will get back to that later.