The best swordsmanship feats are cutting a mountain (Mihawk's slash, S-Hawk's slash).
The first island busting feats are from punches (Garp's punch, WB/BB Quake Punch and Luffy's Bajrang Gun, technically Luffy could have destroyed Onigashima with his punch but he was aiming at Kaido instead).
Punches > swords?