For masteries I'd say he benefits more from 0/9/21
For runes, Standard Armor red/Armor yellow/Scaling MR blue set and whatever quints you prefer. I'd take GP10 because he's more of a poke support.
Philo stone and Heart of Gold start into Chalice and Aegis, I believe would be his core.
Q should be your primary maxing skill unless your enemy has big pokes like Lulu or Lux and your carry keeps running into them, then max Shield and speed buff at level 4, maxed last.
Ward ward ward, win the game.
Your best carries would be the ones who benefit the most from your shield, with them being short range carries like Graves (everyone is good with Graves hurr), Sivir and Corki. Other good carries are those who help you poke, Caitlyn is great because her traps root the target for a quick shot.
Your ultimate comboes best with other AoE ults, for botlane that would be Miss Fortune.