Essential dignity is important. Yet I think it is easily misunderstood, overemphasized, or used willy-nilly without considering a lot of other factors. Assessing dignity, like most things in astrology is complex. Some people will make a really big deal about a dignified planet, but dignity does not simply make a planet good. Dignity is also strongly altered by planetary aspects.
In a very dark example, likely the darkest expression of the day, we see a so-called 'dignified' (in its own sign) and 'contrary to sect' malefic, Mars, in the place of the setting sun. Mercury, Venus, and Saturn as well are all in their own domicile (sign).
Some technical gymnastics:
The Ascendant in Dahmer's chart rises in Libra at the degree of the Sun's deepest debility. The Sun is most exalted at 19 degrees Aries and is at its maximum fall at 19 Libra. I think this is an immediately important factor since it is a daytime chart (the Sun is above the horizon and so is the luminary of the sect in favor). The ruler of the Ascendant is Venus (the benefic of the sect not in favor, it prefers the night). It has 'power' in its own sign, Taurus, so it is good at getting what it wants, even if this is not particularly good for the native; it is in the 8th whole sign house, so does not see the Ascendant. Venus is also rising before the Sun, and so is a morning star Venus, showing her more assertive and warrior-like face. Venus connects to Rahu, the head of the dragon (north node of the Moon), by a close trine aspect, but it is the sign of Venus' fall (Virgo) in the 12th house. The exaltation ruler (almuten) of the Ascendant is Saturn in Capricorn in the whole sign 4th, giving a strong connection to and respect for the parents and tradition - however it is in a tight square aspect to the Ascendant, so we see potential for stress and blockage here. Houses 4, 7, 8 all pertain to death; in the 4th we return to the place from which we came, 7th is the setting place, and 8th is the experience of death, often not our own but the experience of death and upheaval around us (sometimes called a place of transformation). Also of note here, as all these places are highlighted, houses 4, 8, 12 according to the 13th century astrologer, Guido Bonatti, were thought to be houses of varying kinds of imprisonment.
The Moon, luminary of the night sect (not the sect in favor), is waning and is right on the horizon, setting at the time of his birth. The Moon is configured in the whole sign 7th (traditional house of death = setting Sun) with the contrary to sect malefic, Mars, which is in its own sign Aries (making it strong, though potentially reckless). Moon (pertaining to body, nourishment, feelings, and the irrational) receives a dominating square from both Jupiter - which is debilitated in the sign of its fall, Capricorn, and is also the sign of the Moon's detriment - and Saturn, strong in Capricorn, but seeing the Moon in the sign of its own fall, Aries (which it does not care for). Mars receives these squares as well, and since Capricorn is the sign of Mars' exaltation, it is strengthened more (but apparently not for the better). Remember, strong does not equal good. Saturn sees Mars in this square and being the sign of its fall is not especially pleased.
Mars severs, it is related to cutting and knives, it separates . . .
Mars is also antiscia the moon's Node - a point symbolizing connections. Mars|Node can be work connections, physical or sexual or athletic connections, connecting with men, or collaborative or quarreling connections. Mars can also sever or cut connections (Yikes!- when considered literally). Antiscia, being symmetry around the cardinal axis or Aries Point, is indicative of how we connect to the world. Dahmer connected via Mars|Node. Of course, a general Mars|Node connection means a lot of different things as noted, dependent on varied context and circumstance.
The Sun, the luminary for the day, is configured with Mercury, the lord of 9 and 12 and in the curious dual sign, Gemini. Mercury is a youthful and somewhat androgynous character, one that moves between worlds (the underworld and the earthly world). The primary trigon lord for Air in a day chart is Saturn, so both Sun and Mercury are tied strongly to Saturn at the bottom of the chart.
Chart set up from the Lot of Fortune.
(Vettius Valens, a 2nd century astrologer, instructs using the Lot of Fortune as an alternate Ascendant.)
Pluto, lord of the underworld, rises with the north node, Rahu - the insatiable, hypnotic and deceptive head of the dragon. Neptune in 3rd - confusion and deceit in communication. Jupiter in its fall with Saturn in 5th - morally problematic pleasures and recreation; Venus' joy distorted. Chiron and Ketu, the tail of the dragon, indicative of loss, illusion, and wounding in the place of the other -the 7th. Moon and Mars - body and cutting and upheaval in 8th. Venus 'strong' in Taurus (strong for what? pursuing one's bodily desires? pursuing 'matter') and in the 9th, the traditional house of god and spiritual concerns; Dahmer's life was devoted to matters of the flesh. Of note here, Venus receives superior trines from both Jupiter (in its fall) and Saturn, in Capricorn; Capricorn is a notoriously lusty placement for Venus, and so due to the unimpeded flow (trine) it is highly affected by this influence. Sun Mercury in whole sign 10th - public image - Mercury in its own sign is receiving its only strong aspect from Mars, a superior sextile from the malefic contrary to sect. Mercury Mars is adept at handling tools, dissecting for instance [in his case, curiosity gone horridly awry]. Two faces, two places. Uranus in 12th - strange secrets.
This is of course a horrific example of a person with a serious mental illness. Astrology does not show that he is mentally ill, and it does not show that he would harm or kill people. It does show issues with emotions, parents, and others, but astrology does not say what a person will do or how conscious, conscientious, or aware they are.
To recap, it seems clear that essential dignity does not make a planet good, it may make a planet good at getting what it wants, but this might not be good for others, or for the person himself. Dignity does seem to strengthen a planet, but again that can be for better or worse. (Frida Kahlo for instance had an exalted Mars in the 6th (health, disease, accidents) and it was in partile opposition to her Sun in Cancer (the sign of Mars' fall) - it seems probable this powerful planet did more harm to her than it did good.)
One must look at the whole chart. Aspects relaying dignity or debility (called receiving and reception) seem to alter and affect things immensely, as does the way in which one chooses to direct and work with the energy.