We don't know if shanks had or used those in the fight. We also have no context on how the fight went either. we know that characters with weaker haki CAN harm people with stronger haki. this my haki is greater than yours bs only applies when its finishers. name me one instance where it wasnt. if it was a finisher from both sides then sure your point has some footing but we dk the context so it could be anything. we can make an educated guess it wasn't though as shanks has far better haki feats/portrayal