[?] Dealing with wood rot in decorative house fascia.

As part of the fascia (if that's the right word) at the front of our 1930s built house is a wooden decorative piece, see picture of an identical one at:-
I recently noticed that on our house the wood behind the white paint is seriously rotted and will need to be replaced or treated.
I don't know, or have enough knowledge about house-building to be able to tell, if that piece of wood is structural or merely decorative.
Before attempting to do anything myself, I thought I'd better ask in this NG to see if anyone can identify how the shaped wooden piece shown in the picture might be attached to the front of the house - could it actually be supporting any of the brickwork above? - and perhaps give me some advice on how best to deal with the rot.
Could I just use one of the combination wood sealer and filler products that are advertised for dealing with wood rot or is some more serious repair work necessary?
All constructive comments and/or suggestions will be gratefully received.
TIA - Dave.
David C.Chapman - ( snipped-for-privacy@minda.co.uk)
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