At the moment, the difference between Frintezza normal jewel and Valakas upgraded its about 300 m def more for Valakas.
Tezza its the only jewel that cant be upgraded and its not fair for the support classes like domi/bp/tanks that need the resists and cooldown reduction offered by it. Here. i can't equip it on my bp cause it lowers my M def too much and it sux. Please find a way to make it upgradable like all the RB jewels for a better balance.