As of right now equipment is arranged as weapon hand shield hand and you can switch between 2 or more weapons. This can be rather inhibiting when looking at future weapon designs.

Proposal: Main-Hand, Off-Hand

By dividing equipment into 2 hands it provides better flexibility. You could have one sword; a sword and shield; a sword and gun; a shield and gun; bomb and shield; bomb and sword; bomb and gun; two handed weapons.

When charging an attack it will only charge the weapon in the main hand. This means shields will automatically be equipped into offhand and bombs will automatically go into main-hand.

Certain weapon combinations might unlock new special attacks when charging the weapon.

When it comes to switching, currently you switch the weapon in hand. With this system you'd instead switch the equipment set when you press space. So you start off with 2 different sets you can hold, and like how it is now with unlocking more weapon slots for a certain number of days, instead you unlock more equipment sets, so that isn't really different. And yes, I realize that this system would allow you to equip a maximum of 4 different equipment for leveling at a time by default instead of the current maximum of 3 (without paying for the slot increase). You would also have the ability to share equipment between sets, so if you want a shield in both of your sets but only one shield you can use that shield in both.

To go with this system some new weapons could be available, here I name some two-handed weapons

New weapon types:

Shotgun - scatter shot, less damage, reload every 2 shots (double barrel design), reloads quickly

Rifle - longer range, laser sight line pointing off of character, massive damage (comparable to great swords), piercing damage, reload after every shot (bolt action design)

Polearms - long reach, faster than greatswords but don't do as much damage

Great Swords (such as Troika and Hatchet) can use one hand and be slow, or use two hands for a damage and speed boost.