How am I supposed to level in Pagos?

[Aster_E]

Does that mean it I can't level to 35 in Amenos to skip Pagos and start on Pyros? That is of course I'm not bothering with relic but more so going after other rewards like mount etc.

Being able to enter might be once thing, assuming you did the lv35 quest in Pagos, but you won't be able to do anything towards the Pyros phase of the relic without the Elemental weapon. Just level, do the story objectives, and find that you're going to need to go back to Pagos for light grinding and Pagos crystals if you want that weapon upgraded.