I was wondering what wep I should upgrade first. I have a Striker, a Tempered Caliber, adn a Sealed Sword. They all are LV 10 in heat, so I don't need to worry about that. I've got 300 CE, 7k CR (I used to have more, but I bout CE).
Which Weapon should I Upgrade first?
My general advice for constructing a sword loadout (or, to some extent, a mixed sword/gun loadout) is here. The short answer is that you want to own a piercing weapon, an elemental weapon, and a shadow weapon, and use them on the correct monsters. My general advice on which-to-upgrade-first is here.
In order to give you specific advice about your case, we need more information. As Scottish-Archer wrote, what are your goals? Which parts of the Clockworks? PvP much? How many weapon slots do you use? Do you use only swords, or do you want guns and bombs in the mix? Which ones?
I would upgrade the Sealed Sword for the damage type change. Going to Faust or Avenger would depend of what you are planning to do with it (Faust for JK, Avenger for Twins / in prevision of FSC).
it depends what you are going to go onto next. what you are planning to farm etc.