Weapons can have those enchantments on them, like "deal 40 fire damage".
In ESO such effects don't "proc" aka happen with every single attack u perform, since than using very fast light attacks would favor such a system.

So u either have to add a "internal" cooldown how often those effects can trigger or u can mathematically normalize the effect vs the given attack speed.

Eso picked the internal cooldown system and the actual cooldown is around 4 seconds, so your fire weapon will trigger the fire damage effect every 4 seconds of u attack.

The enchant on this set, will now reduce this cooldown by 1 second, so it can trigger every 3 seconds instead of 4.

As u can see effects that last for 3-5 seconds, have a distinct advantage over those damage procs, since they circumvent this internal cooldown. This also favors fire attack damage, since u have a chance to trigger a small fire dot.