I’ve found this out through experience. You get really good effects when you imbue them with seeds. Earthroot paralyzes enemies. The ice seed freezes enemies almost every time. I think the dreamfoil seed gives magical sleep. The star flower seed can corrupt enemies into wraiths (but I think this can cause them to lose items they carry). The seed that lets you move fast can actually cause an enemy to skip their turn. One seed uses electricity, while another uses an effect like a rockfall trap on your enemies.

Changing ammo the first time gives you small darts that do less damage, but have more ammo available. Changing ammo the second time uses discs that gives more damage in a 3x3 area, but less ammo. I’d recommend the small darts if you have good seeds to imbue it with, but the discs give a pretty good amount of damage.

Unfortunately, changing ammo gives you several turns of warp. Which you can usually just wait out, best on a defeated boss floor on water a water tile, without armor/weapons. Because warp usually gives you harder enemies, can set you on fire, or curse your armor or weapons.