ember knight? the manwha?
I see ember knight as a standard shounen action fantasy,
which I think is very different from the Bard Loen's vibe
Bard Loen is more like Frieren and the
elf boy
also "MC uses his brain/experience" criteria is rather hard if the author presents the MC as super smart from the start
with action journey aspect, I'd recommend
Issak, but it is gun, and not sword
for solving with brain(?), not OP, but there are still actions, maybe things like
Risou Himo or
takarauji?
(there are other isekai, like bookworm isekai or the rougo isekai , but they have even less action)
I'd also throw
D Genesis and
Futoku just in case