Guild Wars 2

Suppose I get one of those new ascended items, and I use a transmutation stone to transfer my guild backpack look to it.

Can I still upgrade it to the version that has +Agony resistance?

If yes, will it also take with it my guild backpack’s look?

If no, will I need to get a second item just to be able to get the upgraded version?

that would depend, some back items aren’t transmutable, however if it is, then yes, you can choose the options you want (backpack skin > ascended stats (inc infusion) > additions stats (if applicable)), just like you would any other item. like I said, just depends if it is transmutable, I don’t have one, so can’t say.