Simple suggestion. Add the Ring of Vigour to the RuneX shop for 75,000-150,000 RuneX points. I believe this ring SHOULD be tradeable, so people can't just use it 24/7 for more OP specing. This ring should giver no stat bonus, just allow specials to cost less % of special.
This ring could possibly be imbued, making it 4+ on every attack and defense bonus, along with 4+str and prayer. This would make it a combination of every ring that give's stats that are not imbued. Making it weaker than the rest still give the other imbued rings value, and use.
Option 2:
Make it a rare drop from a boss that is hardly used, dag kings, chaos ele, or add an entirely new boss that has difficulty, such as GWD Bosses or Corp.