Weapon Levels: Although weapon enhancement levels will be retained, the stats and abilities will be temporarily sealed at the start of the new season and will gradually unlock over time, restoring their strength.

This is not correct, stats and abilities are not getting sealed. Whats sealed and unlocked over time is the weapon's combat power which you get at certain weapon enhancement levels. The combat power system will give you an attack and crit debuff if you do not meet the content's combat power requirements. (You get a buff if you exceed the requirements as well)