You guys… lol. Come on.

She’s holding the medal because of Han showing up 5 minutes later. She’s touching the medal as a sort of memento connection back to Han, that’s how she gets a physical representation of his memory over to Kylo to push him over the edge back to the good side. The medal is required to convey what’s going on without words, because Carrie Fisher wasn’t with us anymore to properly act/explain this clearer, and they had to piece together something for Leia to do as a final heroic act. This was a fair trade off. Context, guys.