For the most powerful weapons you're gonna want to start with the blacksmith in ambition mode, make sure to get them to level 30 first since that unlocks the good stuff. The real magic happens when you start stacking skills like slash and explosive to level 10, those are absolute game-changers when maxed out.

Start with a decent third or fourth-tier weapon from normal difficulty stages like wei's chibi, and here's something interesting - the empty weapon slots are actually better for building since you've got more room to work with. While you're working on that, run some skirmish battles in ambition mode to stack up about 150 weapon materials, and don't forget to upgrade your facilities since that'll get you better drops.

If you're looking for really strong base weapons, try farming the capture of wei stage on shu's path with chaos difficulty turned on. When you're actually doing the tempering, stick to fusing weapons that have just one skill each, that way you won't get random results that mess up your build. A good combination to aim for is cyclone with slash since it'll let you break through guards like they're not even there.

For quick leveling, there's this neat trick at the battle of xuchang where you can gain like 10-15 levels in 20 minutes just by repeatedly taking out siege weapons. Once you've got the basics down, start running chaos difficulty stages for those sweet 6-star weapons, and maybe throw on some fire or thunder strategems to boost your material drops. Before you know it, you'll be taking down even the toughest enemies in one hit.