Very bold assumptions.
1. That Karnilla would have to jump planets to steal the Odinforce.
2. That Amora is giving Odinforce to Balder.
For one...arguably he didn't heal instantly. Thor tends to fight in Avengers movies while weakened (only one he didn't was Infinity War). Also Thor is not only Asgardian (who have better resistances than Frost Giants) but he's like...top tier Asgardian. Like take the full force of a Neutron Star Asgardian. Like...get stabbed multiple times and his eye poked out but get up and keep fighting Asgardian.
And if you doubt the Asgardians being more resistant...even outside of Thor's feats we have Frost Giants being disintegrated by the Destroyer, while Sif and the Warrior's Three...were not. Also comics lore about them being resistant to matter manip.