I love this game! The devs put their love into it, too. I spent 12 hours learning, practicing, and dying trying to get an Any% run completed. The rooms are mostly preset, but their order is randomized, and item appearance is also randomized. Meaning that, in order to complete a run, you need to learn how to complete each room without losing a life, and you also need to collect coins throughout the run to save for the shop.
Slash, hands down, is the best left-hand item. The spin attack does 2 damage and takes care of knights.
I didn't realize how nice of a power-up stealth is for the right-hand. Usually I go for jump, since jump saves time, but I'd probably go for stealth in future runs because it's like wearing a mask for each enemy.
Also, it is generally good to carry around health potions or pendants if you can afford them and no other powerful items are available.
Cheers! Download the game and support Tiny Corp, they rock.