Baldric construction

[Peroni]

but then where Tim mentions a button loop fastner I can't see one that matches any beltplate.

I think Tim means that the terminal of the fastener matches the terminal on the 'frog' plate Brian.

whilst I think the bronze 'dagger' is in fact a stylised beneficiarius lance head used as a decorative mount on the shoulder baldric

I agree Tim. It could also be part of a brooch - which were also quite common. The plates say mid-to- late 2nd Century to me too.
I have a plate in my collection of this type - Not with a suspension ring though, and I was unaware that they also had a variant with a cast-in 'frog' like the Chichester set.

I'd venture to say that the suspension loops present on the later Felix Vtere letters were for the same purpose - whatever it may be! The late Roman belt set from Dorchester and finds from the Netherlands paralleling it show that items (possibly pouches/knives) were suspended from the belt rings by small bronze hook devices rather like an open-ended suspension
loop. Perhaps the Chichester type was a forerunner of this fitting?

BTW Tim, are those two pieces at bottom left two halves of a shield grip bar?