Are you sure? The amulet of power you buy for 300 gold from Vendors that reset your spell upgrade points don't void your choices? Cuz they work on the companions specialization points, but then again, companions don't have multiple specialization trees. It also worked in DA2 with the potions that you got in the Black Market (Deluxe edition).
It resets your skill points, it doesn't let you choose another spec. Once you've picked a spec, you have to stick with it, so make sure to save first so if you don't like your spec you can go back. I personally just ran a few side quests with templar and champion on my tank to figure out what I wanted. On my rogue I went straight tempest, it just looked a lot more fun, and it was.
I don't know about better and I didn't play archer, but I liked the flasks a lot, they're fun to use. Frost is probably less useful on ranged but still good if you get something on you(it's great for melee rogue because it freezes on contact, so you can run up to a mob, freeze it, then shatter it with twin fangs and if the mob isn't resistant to cold that's like 2-3k more damage, or 5k if it's a rage demon), but the other 2 flasks are really cool. I'd say put your items on Sera and Cole and go fight stuff for like 5minutes and see which you prefer.
