The Vexillum is supposed to be in the style of Constantine's Labarum.
The general and standard bearer are Magister Militum code SPQR51. The right hand horseman is actually an Essex Miniatures figure that I had in my spares box, but I find that Essex are very compatible with Magister Militum. His horse is Magister Militum.
This is one of the Auxilia units (4Ax) - a few more to paint, but I will get round to those later. Painted up as Auxilia Palatina - one of the Celtae Units. VVV shield transfers were used, touched in with yellow paint to brighten them. Figs are Magister Militum SPQR33.
Here are two elements of the Foederati Warband (4Wb) - Magister Militum Goth figures (code DARK0005). Two more to do for the Patrician West list.
The Light Horse element - Equites Sagitarii. Colour scheme was invented by me ... I like green! Again, Magister Militum figures, but I think these are an old out of production line.