If you don't have a Riven, replace it with [Spring-Loaded Blade].

The Riven:
You really want to have +Range on the Riven because [Tekko Prime] has 0.9 [Follow Through]. Why is this useful? It's useful because it means you're effective DPS is much higher. The Overframe DPS calculator doesn't account for [Follow Through] or Range, so this is a little unobvious because you don't see any numbers go up, but imagine this situation. Your weapon has 100 damage and it takes 50 damage to one-shot an enemy. A weapon with 0.9 [Follow Through] can hit up to 7 enemies and still do above 50 damage. However, without any Range, you won't hit any more than 2 enemies at a time. Once you mod for Range though, you can now hit more enemies and one-shot all of them. The problem is if you have a Follow Through stat of something like 0.4, even if you hit 2 enemies, you're only going to one-shot one of them, so modding for Range is completely useless. Instead just hit each enemy once. At that point, you might as well just mod for more Critical Damage or Attack Speed.

Critical Damage is a mainstay for any crit/slash weapon. There is an extremely limited amount of ways to increase your Critical Damage, so whenever you get the chance, you should try to increase it.

Critical Chance is good because you can get to guaranteed Orange Crits, but you could also go for something like Attack Speed or Faction Damage. You could even use a dual-stat Riven for more Range. It's up to you.

The negative doesn't really matter. You can achieve minus 100% IPS, so if you can get -Impact or -Puncture, you can massively increase your Slash weighting. Otherwise, the usual acceptable negatives are fine with one caveat. [Seismic Palm], which is the optimal stance to use, has a lot of Knockdowns built into the stance, which opens enemies up to Ground Finishers, so you probably don't want to roll -Finisher Damage.