Hello
I did fast concept about knight combo (took random clip art picture from https://previews.123rf.com/images/chromaco/chromaco1110/chromaco111000059/10963541-Warrior-or-Medieval-Knight-Vector-Mascot-wearing-Armor-Stock-Vector.jpg ).
To give this smooth effect you should think about some things. Even best try of smooth move wont work in too fast animation. When animation lasts 1 or 2 frames you wont see difference when you change curves. You need some frames to show smooth move. More frames = more smoothy effect but keep in mind that too much frames and moves may distract the viewer and he wont see effect you want show.
When you make knight or a platform game you should think about choice. Make just a slasher when you dont need any feeling about heavy or soft weapon OR you try to give feeling. Heavy sword will attack slower but player will feel that he keeps powerfull and heavy weapon but also you need more frames to show this, to give this feeling.
When you want to make very fast animations and game doesnt need to give feeling, you can try make several animations as a combo (like I did in my fast animation), not only 3 same moves.
Anyways, you wont make smooth animation when you wont have enought, minimum number of frames.
In the Rar I added mp4 showing animation. Gif after upload showed only 3-4 ...