Without Sap crystal, leveling and pvp will be killed.
Simply a weight of 0,5 (or 1) like material would be a solution no ?
not at all. The op output reduction is clearly intended to introduce more pvp by making op output more rare and thus guilds less likely to share with others so you have to fight over it.
Potions produced by occupations are likely to replace the heal spell on your weapon, and work for the entire team, not just a single target, makes things easier in pvp as well as large groups.
Pop a pot and the entire team is healed, no having to cast a heal on 8 people one at a time (or an expensive and slow heal bomb).