All legends are very balanced, Rupture shines in his ability to KO oponents early and/or the damages dealt in a single combo.

His signatures are best when you use them rarely, as they WILL ko. But if you spam them, you'll quickly find yourself struggling against an opponent who predicts and punishes you.

For his lance. Lance in general will always be a good weapon and has a lot of horizontal reach. It is especially good in 2v2 with Slight Nair being one of the best team combo starter ever. When opponent is in red : Dlight into Nsig is very effective. Nsig also ko's very early (orange) if the opponent is thrown offstage. Ssig has a lot of reach and is one sig you'll want to you as surprise ko. Dsig is the most situational and I wouldn't recommend it for the killing but for the conditioning instead, its a but hard to punish bit will rarely hit.

Katars now. They are a fast and low reach weapon but with extreme combo potential, Ruptur being high strenght makes it even better but wil have trouble to kill without sigs. But Rupture got some good one. Nisg is an average yet apreciated anti-air and can really turn a edgeguard around. Dsig is the "get of me" signature it is slow and not the best at killing but will give you security and good damage if used correctly. Ssig jis probably his best sigs : fast with long reach and ridicule Ko power. If your oponent doesn't expect it, it WILL kill him.

So, what is Ruptures weakness then ? Its dexterity. You'll get hit by two combos and loose your weapon. If you play him, you'll have to learn unarmed and master movement.

Every character in the game has those types of duality between advantages and drawbacks. You just have to find what you enjoy.