These are all words that describe Giles Corey's personality within the context of the play. Arthur Miller bases the character traits off of real-life accounts of Giles Corey, including his unusual fate in Act 4 of the play.
In Act 1, we are introduced to all these traits. The authorial intrusion explaining Corey's character hints at his outspoken nature as well as his courage, giving a hint that his death is different from all the others. The fact that he is viewed as an outspoken individual is reinforced several times: 1) Rebecca Nurse begs him to keep the peace in Act 1, 2) He has several outbursts (specifically towards Putnam) while addressing Danforth in Act 3, and 3) he holds himself accountable for his wife's condemnation because he called her out for reading strange books. This last example also reminds us of his inquisitive nature, since in Act 1 he questions Hale about the meaning of reading strange books.
We see Corey canniness in his many appearances at court, and always the plaintiff as he brags to Danforth. He is able to draw up a professional sounding disposition against Putnam, and is clever enough to tell Danforth that he "cannot clap [him] for contempt of a hearing." We also see his courage in this, sticking to his convictions. He never relents in his efforts to free his wife, and he never tells the court his source. In Act 4 we hear of his final act of courage. While being crushed to death, rather than giving the court the answer they desired, his final words were "More weight." Thus the last words spoken of Corey in the play are "Ay. It were a fearsome man, Giles Cory."