I'm suggesting new combat style related rings (one for each: melee, range, magic). Would be similar like the amulets or spirit shields: 1 for each style and 1 with good overall stats.
Since I mentioned it would be like the amulets are right now:
Amulet of strength (t) - higher melee strength and attack bonus*
Amulet of magic (t) - higher magic strength and attack bonus*
Amulet of ranging - higher range strength and attack bonus*
* compared to Amulet of glory (t), which is the best overall amulet
I would like to see similar case with rare rings. Ring of stone could be the overall ring for example.
As a monster suggestion, I would recommend the Arzinian avatars at Dagannoth cave, who used to drop 3rd age items. They could be easily separated for each combat style and they wouldn't be that easy to kill.
And since strykewyrms and aquanites were added quite recently with such gear drops, I wouldn't put any slayer requirement on the avatars.
When it comes to models, we could use the models of wilderness rings or use fremennik (i) rings.
Let me hear, what you guys think