Has anyone played Earthdawn? It's not a perfect system, but none of them are. It has a lot of interesting systems (many of which D&D created bad adaptations of for third edition, but standardizing the every other stat point above 10 gaining you a +1 is a good adaptation). It's also one of the ideas the Fallout devs were looking at before eventually creating Fallout, and you can see some of the ideas from Earthdawn if you know what to look for.
It's somewhere in between a cookie-cutter class system like AD&D (in that you have classes which determine which abilities you can choose from) and a freeform point-buy system like Shadowrun or Gurps (you spend xp directly to upgrade skills, talents, stats, or magic weapons). Yes, you can level up magic weapons, if you threadweaving (using magic items/magic talent) is higher than the level of the weapon currently. You usually get extra damage or to-hit early from upgrading weapons, with neat powers coming online later. Every 2 weapon upgrades requires research into the history of the weapon, and possibly a small sidequest. You can choose to increase your circle (level) or not when you have a certain number of skills at the next level, which gets you more choices of abilities and some extra HP. You can also just choose a few skills you like and keep increasing them without ever increasing your level. The game doesn't care.
The dice are...interesting. There is a table that tells you which dice you roll (your skill or talent level plus a number based on the relevant stat), but you mostly roll the same dice each time you do that action (Skill 3 and stat bonus of 2 is always a total of 5, and that's always a d8. That sounds more complicated than it is. The reasons for this are giving you the equivalent of +1 when you increase things without moving you off the RNG (remember in 3rd edition D&D when you'd have d20+30 or whatever? Or now when the d20 matters more than your skill?) and to make sure anyone can succeed or fail at any task. You gain the equivalent of +1 on average to your roll by moving up from a d6 to a d8 to a d10, etc. How can you succeed in getting a 10 on a d6? When you roll the maximum on a die, you get an extra die of that type, even if that die was already a bonus die. It's possible to keep rolling maximum on a die forever, but the odds are not great. So your average roll on a d6 isn't 3.5, it's ~4, so the table puts the d6 in the stat bonus + skill = 4 slot. Lower-end characters use smaller dice, so they've got the best chance of getting extra rolls. If you really need to succeed, you've got a certain number of dice per day you can add to rolls. You just say you're using one before the roll, and add an extra (I think) d6. You only critically fail if all of your dice are 1s, so adding an extra die is a good way to avoid that early. You critically succeed by beating the target number/DC by (again, I think) 5. A critical success on an attack gets extra damage, spells give extra duration or buffs/debuffs depending on the spell, etc.
Also, because it's a FASA game there's a mountain of maps, lore, history, plot hooks, political factions, and explanation in every book. At one point, there were some characters from Earthdawn re-used in Shadowrun, but that ended back in first edition (ED is now in 4th edition). It was designed as a D&D-like game where everything is explained. Why are there dungeons? Magic is cyclical (like in Arcanum), increasing then decreasing like a sine wave. When the level of magic in the world gets strong enough, powerful spirits called Horrors are able to enter our world and prey on life here. People knew about this in advance (which is also explained in-game), and built various forms of shelters to protect them (domed cities, underground cave structures, entire forests of thorns, underwater villages, etc. Remember when I mentioned Fallout?). Some of them were unsuccessful and now contain monsters. Why are there monsters? Creatures who were attacked by the Horrors were corrupted. Why are there classes? That's how you were trained to make use of your magic (even fighters are powered by magic, and have interesting abilities). Why is it called Earthdawn? That's the name of the airship the dwarves sent out to start letting the shelters know it was safe to leave. You adventure to gain more renown, because that's how you increase your abilities. And your characters know that. Now that the magic level has fallen enough, the strongest Horrors are forced back to their world, and the shelters are opening.