The powers are described as what
Delivers utter certainty.
The ten powers, which shall later be explained, are characterised by giving one utter certainty. Since with utter certainty one can be characterised as undisputed, they are called the powers.
The Buddha’s confidences are
In essence firm security. (6.210)
The four types of self-confidence are as follows: (1) ’When having declared, “I have reached full and complete awakening,” there will be no occasion when anyone – no ascetics, brahmins, gods, demons, or even Brahma – can reasonably challenge me by saying, “Oh no, you have not come to a full and complete realisation of all phenomena,” [and so forth].’ (2) ‘… “O, I have exhausted the defilements,” … “Oh no, you have not exhausted the defilements,” [and so forth].’ (3) ‘When following the teachings I have given about what the impediments are, there is no grounds for the claim, “these are not impediments,” [and so forth].’ (4) ‘If one dedicates oneself to the noble path of deliverance that I have taught, one will eliminate suffering and find deliverance, and there are no grounds for the claim, “one will not eliminate suffering and find deliverance,“ [and so forth.]’1
These are characterised by a firm security, since no one at all is able to alter this.