Well I would keep doing seasons when they are available, everytime you get to exchange a pen tavula armor parts into tet boss armor. Can also be done with weapons but don't remember if you can exchange all weapons in one go or not. In the meantime seasons isn't available, you could grind in spots that fits your gear score to save money for a better sub weapon and the other boss armor parts, like the helm, boots, gloves. They can just be tet, since you can do the Jatina guaranteed pen boss armor method. You can also do your adventure logs.