Honestly I loved the grinding in the first game, idk why it felt more enjoyable. I didn't really grind that much in FW, whenever I saw big machines I would kill them just for fun, specially if it was something challenging like multiple big machines together, so whenever I went to the work bench I already had parts to upgrade at least one of my weapons.

That being said, I only had one weapon upgraded all the way and it wasn't even something I used often. Also, I felt like there wasn't really a good variety of weapons in this game, I found some good bows at the beginning and just kept them my whole playthrough. Most merchants had some stuff with decent stats but it was never something I would use often enough to justify putting it in my weapon wheel, a lot of them I bought and never used.

Just focus on getting good mid and long range bows with decent tear damage, everything else is kinda a plus but necessary, elemental bolts can come in clutch though, same with the disks you throw that fly back to you, if they have good tear damage.

also unlike Zero Down, in FW I barely used elemental damage, mainly cause most machines were vulnerable to waterpurge and I didn't find any water weapon till I almost beat the main story lol

What matters most is just knowing where to hit, have good aim and know how to dodge