greatswords were not built for fast combos but since they have good and destructive damage potential they were widely used by hunters even me. if you're gonna use greatswords for the first time i suggest using a hit and roll tactics by hitting the head of the rathian when you're comfortable enough u can use it it the quest a troublesome pair but i suggest using siegmund (Bone blade-bone blade +-Agito-Agito+-Dragon Agito-Golem blade-Golem blade+-Siegmund and another advantage of it is its ability to easily break or cut certain wyvern parts like tail,chest,head, and wings because of its wide range