Rolemaster solved this circa 1980.
Seconded. Though the whole system was very 80s... The clunkiness was somewhat everywhere.
It seems very complex, and has a reputation for being complex, but as long as you can do a bit of addition I would say it's less complex than most modern editions of D&D. The tables do a lot of the heavy lifting.
I'd say it's not
complex. You roll a d100, add a bonus that is mostly static, substract a GM-provided modifier and refer to the chart for applicable result. It's easy, as in a middle schooler can do it. Even if you'll mostly use the same table during the fight (you're wielding a broadsword, you're unlikely to change your weapon mid-fight -- though there is a tactical sense to do so sometimes -- and the enemy won't don another armour mid-fight either... so you'll mostly use the same table...
It is, however, clunky.
Because, the crits are referenced on... another table. For example, if I roll a 94 with my broadswoard attack, against a breastplate wearing opponent (AT 17) and I'll deal 6 HP damage. That's very low, and it is mostly possible that wear from the fight will be the only way to kill him or a very lucky shot. If however, I do the same attack against a robe-wearing wizard (AT 2, notice that it is WORSE than AT1, naked), I'll do 14CK, which is 14 HP.... and CK means a severity C critical... that you can check on the Krush table (the second letter defines the type of critical).
So, you flip your Arms Law manual, because weapons can do several types of criticals, and get to the Crushing Critical:
Where you roll your dice, and you check in the C column. A roll of 08 will transform you 14 damage into 17 damage, while other results will get specific results, both narrative (a wrist-shattering blow in the left arm, foe stunned on a 76-80 up to 100 (+30 damage, foe is blind, stunned and unable to parry 24 rounds.
This is nice. This isn't complicated, but it is cumbersome. In this day and age, I'd rather have a computer program solving that, potentially on the GM's smartphone or tablet. I dislike computers at the table, but this one of the reasons I'd welcome them. It maes the things fluid. Type the parameters of the attack on your app, click "result".