some questions from ds3 newcomer

[fading agate]

Deep isn't a status effect, it's just Dark damage that doesn't scale

not always an increase in damage

as it doesn't scale with any of your stats, other infusions will do better at higher levels

(whether it does more damage also depends on the absorptions of your target)

as for poison:
for PvE infusing a weapon with a Poison Gem isn't really a good idea, a good chunk of the bosses are immune and those are the only enemies you'd realistically get good use out of poison

in PvP i'm pretty sure it's better to just use one of the weapons that has innate poison buildup with a physical infusion and put rotten pine resin on it