rough draft of what is to be used for equipment to maintain game balance.

Bad: persistent mdef effects, persistent lifedrain effects, persistent manadrain effects, persistent dodge or accuracy effects (beyond that applied by stats), weapons above 100 damage (may be more reasonable at a later time), monsters above a level of 50, monsters with stats built to compensate for a 'lower level'

persistent regeneration effects, mp or hp persistent aspd effects not applied by base stats, persistent consumption bonus effects (malus may be reasonable later), persistent critical defence effects, persistent full restart recover effects, persistent physical immunity effects, persistent magical immunity effects, persistent blind/sleep/poison/freeze/silence/stan/curse/confusion/stone effects

class based physical damage reduction effects, class based magical damage reduction effects, drop rate enhancers for non quest purposes, spells which have significant dps when compared raw to physical attacks, monsters that have high physical defense, equipment that has high physical defense, nonrandom block type physical or magical damage reduction, and there is no way I have covered everything because the combinations of things you should not

Next, bad for now: persistent splash effects, nonrandom splash effects, physical elemental damage, most forms of rate modifiers, long attack/short attack modifiers, double attack probabilities, stun modifiers, hide modifiers, non-base status effect resistance in any form