If you've deluded yourself into thinking Ryokugyu must be a novice with a sword just because he prefers spamming his fruit for weaklings, let's just consider that:
Even the type of sword Ryokugyu was given points to him being skilled with swords
Oda gave Ryokugyu a
grass-cutter sword
A sword characterized by being small, light-weight, in of itself not very powerful unless you are skilled with it
Compare this to a sword other sword-users who wield a blade, but aren't very skilled, tend to have:
Oda gives unskilled sword users large swords, or ones with innately strong attributes, usually because that they are using the sword just to give themselves an edge in combat and not as something they are genuinely skilled with, so they go with a sword that's beefed up and OP
But Oda gave Ryokugyu one of the weakest types of swords that he would
have to be skilled with in order to get any usage from it