Two words: VARIETY & SPECIALIZATION
What I mean by that is increase the variety of ways to build out the melee weapons, with new stances and attach stats to the stances, both positive and negative. Doing this will require players to specialize more, when it comes to what the goal of the weapon is. Want a balanced weapon, then use the balanced stance, but that may come with flat stats or even no stats, preventing you from maxing out your crit or status. Want a Critical Chance/Critical Damage build, then use that stance, but that will decrease your status chance and maybe even your speed. This can be done with combinations of stats, much in the way the dual stat mods work, but can include negative stats as well, like Rivens do.
Combine a system like this with how Zaws work and you can really bring out new ways of min/maxing melee weapons, which in reality is what most players want. People love to min/max, otherwise why would people collect hundreds of thousands of Kuva to blow on rerolling Rivens.
The end result is much more variety in how people are using the hundreds of melee weapons, especially the niche ones that are rarely used except for MR, and expands the customization of Zaws to a new degree.
Obviously, this would be a large undertaking, but in the end could provide new avenues for future updates of Primary and Secondary weapons. I'm looking at you Kitguns!
Just an idea from a fellow Canadian. Keep up the amazing work!!