Good question.
There is at least one sutta defining panca bala the other way: “Punakūṭa Sutta (AN 5.16)“:
“Pañcimāni, bhikkhave, balāni. Katamāni pañca? Saddhābalaṃ, vīriyabalaṃ, satibalaṃ, samādhibalaṃ, paññābalaṃ—imāni kho, bhikkhave, pañca balāni. Imesaṃ kho, bhikkhave, pañcannaṃ balānaṃ etaṃ aggaṃ etaṃ saṅgāhikaṃ etaṃ saṅghātaniyaṃ, yadidaṃ paññābalaṃ. Seyyathāpi, bhikkhave, kūṭāgārassa etaṃ aggaṃ etaṃ saṅgāhikaṃ etaṃ saṅghātaniyaṃ, yadidaṃ kūṭaṃ. Evamevaṃ kho, bhikkhave, imesaṃ pañcannaṃ balānaṃ etaṃ aggaṃ etaṃ saṅgāhikaṃ etaṃ saṅghātaniyaṃ, yadidaṃ paññābalan”ti.”
On the other hand, the sutta Tobias quoted is about Sekha bala.
I am not sure what the difference is. But a Sekha means “one in training”, basically anyone below the Arahant stage.