I just saw this coin, which I believe is an unofficial issue. The style is really good, but an official Trier coin would have a mintmark of TRS instead of TSR. I think that the SV above the mintmark also only appears officially on coins from Lyons. This example is also a little smaller than usual at 18mm and 2.03gm...normally this coin is circa 20mm.
Here is another nice example
Here is a neat one for Decentius
20mm 5.4gm
The archetype of an ideal imitation, I love it.
The bust has something reminding me Julian's one. I'm thinking to his cuirassed busts on the FTR from Rome like this one for exemple.
here's another nice Decentius...the seller, however, thinks that it is an official mint product that is unlisted
DN DECENTIVS NOB CAES / VICTORIAE DD NN AVG ET CAE /
on shield: VOT V MVLT X / in field: SV / in ex.: palmbranch AMB palmbranch.
Grade: uncircluated; dark gray-brown patina.
Reference: RIC VIII, Amiens 12 var (bust type, field marks & mintmark). Unpublished variant.
Here is my only Magnentius barbarous, nothing like those you have posted Victor but it does have a well done Obverse.