Anna’s ice form is so cold, that it actually starts to freeze Han’s sword as it gets closer to her hand. I never knew why it broke but now I do. It’s so beautiful and terrifying at the same time. Which would make sense why Elsa could touch her because with her powers the cold/ice wouldn’t bother her. But if anyone else touched Anna her frozen form might have hurt them. that means Elsa went from being the only person who couldn’t touch Anna to the only person who could.
A lot of people love Elsa in Frozen, but I'm more of an Anna girl myself. While Elsa says "the cold never bothered me anyways" Anna is completely bothered by the cold, but she overcomes that because of her determination and love for her sister. Elsa ran away from her fear and Anna went face first into it with no plan of how to fix things, but with the hope that somehow, just maybe, she could help makes things right again.