I could spend a lot of time on equipment, but I intend to keep this simple. Besides, the only equipment most people are interested in is weapons and armor, so I'll focus on that.
Each weapon has an ability score used for attack, an ability score used for damage, and a constant added to damage. This constant is between 0 and 5, most commonly 3 for most one-handed martial weapons. Most weapons use Agility for attack rolls, and Fortitude for damage rolls, but there are exceptions.
The first exceptions are the crossbows, daggers, and rapiers, which all use Agility for both attack and damage. Each of them has a disadvantage. Daggers have a 0 damage bonus. Rapiers are slightly better at 2 but are special weapons requiring particular training. And crossbows take significant time to load.
The other exception are heavy, two-handed weapons. These use Fortitude for both attack and damage. There are a few special one handed weapons, such as Dwarven waraxes, that have this feature as well. Normal swords need Agility for attack and Fortitude for damage.
Armor will work closer to a cross between 5e and 3.5e. They'll be divided between light, medium, and heavy, though unlike 5e, you don't need training in light to get training in medium, though you will need training in light or medium to get training in heavy. Like 5e, the armor class will be calculated using a base value plus Dex (or in this case, the higher of Agility or Mind). However, the maximum Agility or Mind bonus allowed will depend on the specific armor, rather than just being dependent on the light, medium, or heavy type. I'll probably also bring back an armor penalty based on the specific armor, though it will not grow to the ridiculous heights it could in 3.5e and Pathfinder.
One thing I want to do more with is Crafting. I want rules to craft not just ordinary armor, but magical armor. This will take two forms: casting enchantments on ordinary armor, or crafting (or improving) armor with rare materials. Those materials can be quest rewards or discovered while adventuring, but they usually can't be purchased. Whether using raw materials or casting spells, there will also be an estimated cost in gold, which will probably be about a quarter of the purchase price of the item (most items cannot be purchased, but there is an attached price for reference). That amount represents costly materials and components needed to craft the item.
Crafting an item is a long-term task. To complete an item will require a number of success tokens proportional to the difficulty of creating the item. Each day, the player spends an amount equal to the total cost divided by the number of necessary success tokens, and rolls a Crafting skill check. Each degree of success adds a success token, while each degree of failure subtracts a success token. The item is complete once the number of success tokens equals or exceeds the number needed to complete the item. Notice that very good rolls could result in the project costing less than the estimated cost.
Casting a spell on the item is a ritual, that usually takes multiple hours since the spell point cost of making an enchantment permanent is greater than a magus's total spell points. Remaining focused on the spell during the course of the ritual generally requires multiple rolls.
Crafting tends to take days, rather than hours, but it has the potential to cost less, and a failure on one roll doesn't necessarily ruin the project. Moreover, projects may be put aside and returned to later. Casting a spell takes hours, but one failed roll means the whole spell is lost, along with any material components.