in upgrades, what does "[|greatly |significantly ]increased" mean exactly (in %), and do they stack from different items??

[rumpelstiltskin]

in general though, i find this random loot system tedious and exploitative, in that you have to constantly keep looting random drops to match your level, and then re-apply traits without an option to recycle the existing ones. upgrading stats looks like a trap, since each successive upgrade costs more, and pretty soon it'll be easier to just replace it with a new drop.
at least your character doesn't have to look ridiculous due to constantly changing gear from mismatching styles since they added "change appearance" option, but while we are at it, i wish there was an option to keep the current appearance even when i change gear.
it's not really a hate post, as i like the game overall, but prevalence of this gear system in modern games saddens me. witcher 3, dos:2 both had it (among others), and it was a big con point in otherwise great games. was it invented by diablo?

[Aethrys]

Upgrade materials aren't exactly hard to come by, but you don't even really need to upgrade imo. Can get by quite easily without it.

[rumpelstiltskin]

ok so i went down and tested it myself, and looks like a tier-3 single spell (expelliarmus in my case) damage upgrade is +15%. upgrades do seem to stack, even multiplicatively, which means with 6 level 3 upgrades for the same spell it'll give about +131% damage. i guess bottom line is that a single upgrade is completely negligible, and with a full suite it's ok, but not particularly game-changing either.

[rumpelstiltskin]

so after a bit more testing, and with some info from this page https://www.reddit.com/r/HarryPotterGame/comments/10yq9sk/trait_stacking_tested_on_2_traits/, i can conclude that there are both multiplicative and additive (per clothing item) traits.
- single spell damage is 15% multiplicative (+130% full suite)
- concentration (all spells) damage is 9% multiplicative (+67% full suite)
- unforgivable (damage to cursed targets) is 30% additive (+180% full suite)
- and the winner is herbology, which is 75% additive (+450% full suite). not sure if it's intentional, since it's better than traits for a specific plant (at least for the tentacula)