@Riot, why not just let Thresh proc Relic shield execute?
So out of all supports Thresh is second to last place for average gold earned: http://champion.gg/champion/Thresh
It's SOOO tedious and awkward to proc Relic shield on him. I realise there is a skill aspect to it, but that doesn't mean it feels good or rewarding. It feels like you're fighting your ADC for last hits, it doesn't feel healthy at all. If it isn't already bad enough during laning phase, trying to get any procs off during the rest of the game is a complete nightmare.
Either let Thresh proc execute on Relic shield, or make another support item that gives just as much health.