@Doodads
I think you are mistaking the power relations here. Back against Charybdis, the only ones who managed to solo one-shot a Megalodon were:
Benimaru, Shion and Ranga.
Diablo appears to be the strongest of Rimuru's subordinates, but he is busy with dealing with Farmus. After that come the 3 I just listed. Benimaru is the head of the military, so he is out because the army went to clash against Clayman's army which is led by the newly introduced Yamza. Then there's also an additional group that goes for the castle, as we learned this chapter, though that only came up after things were already underway. Finally Veldora, the strongest out of everyone, is kept at home for defenses.
That leaves only Shion and Ranga. In Tempest they share the spot of 4th strongest together with Benimaru, after Veldora, Rimuru and Diablo. How exactly are they "not particular strong"?
And to everyone here: Does it really hurt so much to not throw untagged spoilers around about events that will only be covered in the manga by the time it's like the year 2026 or so?
The untagged spoiler-posting has reached never before seen heights.