The gem was in his hammer. A hit from his hammer could life wipe a planet, but a hit from his hand dont. In the movies, when someone hold a gem is very hard to endure -if you are not very strong you just die (explode), and you can see blue energy lines in the body.
Is to hard to most of people, and i guess even for Ronan, to keep this power. Thats why he put the gem in his hammer.
Thats why i think he dont get any boost from the gem. Because it was not direct linked to his body.
Okay, I've revised the list order given the input thus far and I added Agents of Shield villains to the list.
I'm still leaning towarsd Ronan with Orb > Malekith with Aether. I'm still really up in the air with Killian. If lowered in the group below him where exactly would he fall? Thoughts?
1. Thanos
2. Ronan (with Orb)
3. Malekith (with Aether)
4. Kurse
5. Laufey (with Casket of Ancient Winters)
6. Loki (Chitauri Scepter)