The spur series consist of fairly straightforward swords. Their distinguishing characteristic is their lunging and their useless charge attack, and winmillion's projectile after every slash.
The addition of a projectile to the spurs (especially winmillion since the thing has projectiles after EACH slash) is a bit odd considering you lunge much farther than any other sword in a full combo.
Being one of the few swords with a projectile (along with the wrench wand, avenger and faust series) it seems that it should focus less on the actual slashing and more on it shooting projectiles at enemies.
I would suggest you improve the projectile. The huge energy disk the spur shoots is far too slow to be of any use. It's damage is somewhat weak and it doesn't make up for the fact that most enemies and players can easily dodge an attack such as this. It's range is also shorter than the lunging distance of an entire combo.
I would prefer a quick moving projectile that has somewhat better range, but less range and maybe less power than that of a sealed sword variant.
Also, a quick note on the winmillion:
When you use a gun or any type of projectile, the enemies will dodge or block whenever they can and if they are able to. Unfortunately the winmillion shoots projectiles that causes many enemies to dodge or block the attacks. This gets very annoying as the projectiles don't have enough range to justify shooting enemies from a long range, enemies that dodge often dodge out of lunging range, and enemies that block tend to nullify any damage the combo does.
It would be great if you could remove the projectiles after each slash.
However, the lunge range is what makes the spur series different from every other sword on the market. It's also decently fast, but this is an easy way to commit suicide if you were trying to attack a group of enemies. I would prefer that you make it safer to lunge into enemies.
Also, the spur has great potential for a potential 5* weapon.
I mean, could the motor in the spur only generate blasts of cutting winds?
I think the motor could and should be used to generate more kinds of damage, like the ability to propell fire towards enemies.
Also, the graviton's low walking speed makes trying to use it largely suicidal if there's an enemy behind you, and the effect and damage doesn't seem worth the slowdown while charging for a pretty long time.
The graviton should be able to do a bit more than just sucking in enemies that are capable of moving. It should be able to alter the trajectory and speed of projectiles.
And rather than have graviton bomb knock everything back out as soon as it explodes, why not have the black hole collapse within itself just explode without shooting all the enemies out? This trait does screw up my plans sometimes in arena levels.
I think the Winmillion's projectile is fine. The damage it does is incredible (almost on par with 5* weapons, actually, if you manage to land both the slash and projectile each time, which you can if you knock the enemy straight back instead of to the side. The lunge and shoving distance, in fact, is incredibly useful for pushing enemies into corners where they'll be easy to land full combos on.) and the quick combo as well as the lunges make it a great weapon with very many uses.
However, I do feel that it needs it's charge attack reworked and a 5* upgrade added. It simply feels irresponsible to have a weapon that's viable for it's unique playstyle, but have it be made un-viable simply because it doesn't have the stats it needs.
If I may make a specific suggestion, I think a good charge attack suitable to Winmillion would be a literal charge, where the player lunges forward the distance that (or maybe longer than) the full Winmillion melee combo lunges you and damages and knocks back/aside enemies that are in your path. Just something that emphasizes Winmillion's role as a mobile melee weapon instead of just another projectile charge attack (and a mediocre one, at that) that so many of the current weapons have.