But his chagrin sprang not at all from that.

His cold anger was purely personal.

He was a gentleman--of the fine flower, as he would have described himself--of the nobility of Portugal; and that a probably upstart Irish soldier--himself, from Samoval's point of view, a guest in that country--should deny him his house, and choose such terms of ill-considered jocularity in which to do it, was an affront beyond all endurance.
For a moment passion blinded him, and it was only by an effort that he recovered and kept his self-control.

But keep it he did.

You may trust your practised duellist for that when he comes face to face with the necessity to demand satisfaction.