Resonance Stones that can be put in armor usually have an (Armor Only) Note in there description, or its a Resonance stone that can be put in either Weapons or Armor. Resonance Stones that work with both appear to have a different effect for when in a weapon or in Armor.
Ice Vortex Resonance Stone:
In Weapon: 3% chance to add +15 Ice damage to your weapons damage on hit.
In Armor: +3 Ice resistance
I believe that is what the effects are. As you can see its capable of being put in both and likewise has different effects for each. There are many different ones and I doubt they're all store buyable =p.