Originally Posted by
Slashley
The attack one. They're just too good to pass up on. Don't look at the skill they buff, the passive you get from skill leveling the Relic weapon is wayyyy more important almost always.
To be noted is that generally, Hercules is considered to be the go-to Soul these days as her offensive Relic weapon is insanely good, plus it works insanely well with Provisional Forest (the best EX skill if you can support it). You seem to really like playing a tanky build, though. If so, I guess you can go for Joan's offensive weapon as well.
Even then, I'd highly recommend you bring Sniper Shot over Medic Potion, as dropping enemy Def and Atk by 20% is a huge deal.