
If it's a plain horizontal swing, keep in mind that from an rpg viewpoint every horizontal circle appears as ellipse with a 4/3 width/height ratio.
this optimal shape however can get squished and transformed, because hip, ribcage, shoulders and elbow are changing their angles in (swordfight) movements.
Usually swordfighters tend to lie weight in the slashes, at least if we are talking about weapon types like classic swords, sabers and katanas.
If you want to force the projection impression, stay with the idealised shape.
Since I assume we are talking about game-art:
The other thing you have to keep in mind are the gameplay aspects.
Does it hit only the enemy in front of you?
Does it hit enemies at a cone in front of you?
Is the anticipation before the animation short enough that it feels responsive enough in the game?
How long it will take depends strongly on how much tweaking it needs in order to get a responsive gameplay.
Looks good is not the same as plays good. Never confuse those two things.Looks alright, but plays well is better than looks great but plays shit if your goal is to make a game.
Just doing the animation and considering all the edits you will definitely need to ship a product, I'd roughly calculate with at least a day of work per animation like this in the planning stages of a project.