Meanings according to Rider-Waite:
ASTROLOGICAL SIGNIFICANCE: Mercury/Mars as a symbol of sharpness of mind and determination, or Mercury/Jupiter as the increase of knowledge and higher Reason.
ACE OF SWORDS Each of the Aces personifies a certain chance. The Ace of Swords corresponds to the higher Reason, that power of cognition which leads to clarity, consistency, and the capacity to make decisions. In contrast to the following card (the Two of Swords), which symbolises the destructive force of doubt, here the work of the mind is carried out in its purest, brightest, and most liberating form. All the sharpness of mind at our disposal must be directed toward penetrating to the essence of the problem, without losing sight of the overall picture, without drowning the problem in a dispute over words, and without dismissing it as "insignificant" — so says this card.
From the book: Hajo Banzhaf. THE TAROT HANDBOOK. Translated from the German by E. Kolesov. Publisher: Centre for Astrological Research, 1999.
ACE OF SWORDS Astrological equivalents: Aries, Cancer, Scorpio, Capricorn, Mars and Pluto, the conjunction of Mars with other planets. The First, Fourth, Eighth, and Tenth Houses. The ACE OF SWORDS symbolises Force, the Seed of Force. Something is being born and beginning to ripen. It is difficult to indicate a clear distinction between the upright and reversed positions of the ACE OF SWORDS. One can only say that the upright position acts more strongly than the reversed. The ACE OF SWORDS is regarded both as the germ of Force and as the Medium that has received this germ. With such an approach, one needs to have a clear notion of the boundary between seed and medium. The seed is maximally separated from the medium. It has not yet sprouted into it. The medium may destroy the seed, or the seed may actively act upon the medium. The suit of SWORDS also symbolises direction. The whole question is where the action of the Force will be directed — outward or inward. On the level of the body, the ACE OF SWORDS may indicate the beginning of a passion, an illness, or some undertaking. It can be said that the ACE OF SWORDS symbolises a new action or a new act of will. Initiation may also come through the ACE OF SWORDS — that is, the connection to something new. On the whole, the ACE OF SWORDS is the most "energetic" card of the MINOR ARCANA. The pitfall — the Sword in the service of base interests. Violence as a means of solving all problems.
UPRIGHT POSITION In the upright position, the ACE OF SWORDS symbolises determination, courage, initiative, strength, might, activity, fertility, prosperity, intense emotions, passionate love, conquest, challenge. It is clarity, breakthrough, division (the cleaving stroke of the sword), penetration (of the blade into the flesh). The inseparable bond between victory and suffering. The victory of the Sword is always the elimination of comfortable half-measures, indolence, self-pity. In dealing with the ACE OF SWORDS, we enter into interaction with factors which in a horoscope would be represented by such planets as Mars and Pluto. The ACE OF SWORDS expresses the rhythm and vibration of the sign of Scorpio to the greatest degree. In part, Aries is also attuned to the ACE OF SWORDS.
REVERSED POSITION In the reversed position, the ACE OF SWORDS turns its energy upon itself, thereby symbolising destruction. Illnesses, destruction in all manner of manifestations. In the worst case, the ACE OF SWORDS may signify the undermining of vital forces and, in principle, a lethal outcome. However, this is a very rare phenomenon. The indication of a single card in a spread is usually insufficient. The reversed position of the card may signify an attempt at initiation, an attempt at movement when conditions have not yet definitively formed. That is to say, the Medium, as it were, suppresses the undertaking; but in any case, the ACE OF SWORDS always signifies some trial of strength.