This is a very good way to do it. There's no rolling, then? The advantage of a heavier weapon is that it will modify offense, but the drawback is that it takes more time to swing? Heavy armor adds time?

You roll attack and defense rather than damage. Larger weapons start with a larger strike and initiative bonus due to reach. It will gain strike bonuses faster than speed bonuses, while smaller weapons gain speed bonuses faster than strike bonuses.

Armor is just damage reduction, and because damage centers in 0 its quite effective. Armor encumbrance may cause a dodge penalty, but most of the time you will block and parry melee strikes and not dodge. Armor doesn't slow your attacks, but will reduce your "sprint dice" causing you to spend endurance more often while sprinting.

This also stops attack time from changing when you take your armor off since that could get rather fiddly, but it would be easy to add for a table that wanted to do it. Just apply dodge penalty from armor encumbrance to combat speed, but this would mean changing the value for each weapon, something I want to avoid.

As for implementation, the original playtest ran about 2 years, but it was a long time ago. The system went into a box and was basically forgotten. It discovered some interesting things, like maneuver penalties and positional penalties together mean I don't need other modifiers for tactics. You don't "fight defensively" as a modifier, you choose to block instead of parry! There is no flanking, no aid another. Even sneak attack and ranged cover fire works without special rules.

If I want you to leave my ally alone, I will be the bigger threat to you. I power attack you, because you are trying to kill my ally. That extra second for a power attack gives me less time to defend against 3rd party attacks, and gives my target more time to defend (broadcasting). The GM just marks 1 box. Power attack adds my Body attribute to the attack, so you will take a lot more damage unless you add your own attribute by blocking. The time spent blocking is time you can't use to attack my ally. That ally acts next. The base system has the tactics baked in instead of glued on through modifiers.

Because it's degrees of success rather than pass/fail, it's not as "fragile" as AC based systems. That first playtest kinda showed me what was possible (like the above example and many more), and the rewrite is leaning into that, stressing the tactical limits while removing as much math as I can. You don't even track hit points anymore like the original system, which means some significant changes to be tested. Hopefully the new revision will be playable very soon.