Relic Shield line passive feels weak mid- to late-game

I play tank/utility Braum support a lot and I find that once the team groups up to push a lane, it is almost impossible for me to execute a minion with Relic Shield or anything that builds from it, as the damage-dealing champs eat up a wave before I can get three or four hits in. This is annoying from both a healing point of view and a gold one, as it is almost impossible to generate gold with the item mid- to late-game when I'm with my team. (Unlike Spellthief's Edge and Ancient Coin, which give me gold for attacking champs [I do that all the time in teamfights, heh] and existing, basically.)

Do other folks agree that Relic Shield could maybe use a buff, even if it's just +2 gold/5 like the other support items? Should I be building better (I currently don't build any damage items, opting for tankiness and utility instead)? Do I just need better runes (still working towards completed rune pages, as I only started caring last month)? Do I simply need to last hit better?

Tips or support appreciated. Thanks people!