Just wanted to write this topic to notify everyone that flag juggling will return in Halo 5: Guardians from its unfortunate absence in Halo 4. As stated by Greenskull in one of his latest videos, he says that the feature has returned while showing off some sweet flagnum screenshots. So yeah, there you all go. Hope you aren’t confused anymore 
Posted 10 hours ago already bud, next time use the ‘search’ function. Thanks for the info though!