While these proofs are nice to get some hero points, they become quite useless after getting your elite specialisation. Ofcourse you can spend them on siege but there are many other ways to get those. Buy from TP buy from vendor with some silver/badges, use a siege book and some mats to make them superior.
So my suggestion is to have a vendor with unique skins only obtainable by these proofs of heroics so we, the wvw players, have something to show off vs our spvp/pve comrades. I have no idea yet how much points per skin but this is just a suggestion to give them a bit more value.
Edit: typos.
Big Babou, Ranger for life.
Madness Rises [Rise] – Banners Hold.
Don’t argue with idiots, they pull you down their level and own you with experience.