Orson Randall was a previous Iron Fist who just like Danny wound up in Kunlun through an accident then decided to skip out and do his own thing. He was part of a super team in operation around world war 1. And one of the things he did different with the power was to channel it through a pair of guns he used which is very appropriate considering that was the era of the pulp heroes. In his time in the comic he taught Danny how to use his power more effectively and variably. Remember Danny learning (and then apparently completely forgetting) how to use the Iron Fist to heal? Well Randall used the healing power to keep himself young and healthy which is why he was still around to train Danny.
Now the bad part is the guns themselves weren't filled with the power. He just channeled it through them so Danny shouldn't be able to use them that way if we go by the comic version. And Colleen has never been given the power of the Iron Fist so that definitely comes out of left field.