[calmon]

To bless you need commanders with priest level. You can script them in the army menu with 'Cast a specific spell'. Choose 'Blessing' and some of your sacred troops will be blessed. Priests with priest level 3 and higher are able to cast 'Devine Blessing' which bless all your sacred units on the battlefield.

The starting units are very good in most cases. You normally get better troops trough better spells. Try to research 'Conjuration'. Your mages will be able to cast some mighty summons if you research one of the higher levels.