@SeriPSO2 I think that's separate from the question they're asking. They're asking about "base" weapon in regards to affix transferring, so that they don't waste time augmenting the wrong weapon, not what weapon's at the earliest part of the chain.
When you get a weapon from a shop that requires you to trade in multiple +35 weapons for it (like Starquake or Atlas EX), there'll be an extra step in the trade-in process that asks which weapon you want to transfer the augments/etc from. So you can slam your big augments on your Profound weapon, or your Detonation weapon, or your Claudium, etc, it doesn't actually matter which one, just make sure it's the one you choose in the augment transfer step when making the Starquake.
Although, it's probably better to set up the augments on the Profound than one of the other weaps anyway, because Profound has S1/2/3 slots like Starquake, where some of the others only have S3s. So if you put the augments on something other than the Profound, you'll have to add your S1/2 abilities afterwards (but that's not a huge issue because transferring an S augment is pretty easy).