Planets in signs and houses Strength and weakness of planet

 strong natal planet protects and promotes its general significations and the significations of its mooltrikona house. Any planet is considered strong when its longitude is between 05º to 25º in a particular sign and it is not in the state of weakness. It can increase its strength further if:
a) it occupies own or good navamsa and other divisions.
b) it is under the close influence of the functional benefic planets.
c) it occupies its exaltation, mooltrikona or own sign.
d) it closely influences the most effective point of the house.

The affliction is special or multiple i.e. when it comes from:
1) a conjunction with/ aspect from the most malefic planet,

2) an aspect from a functional malefic planet placed in a dusthana,

3) a conjunction with Rahu or Ketu (Rahu-Ketu axis)

4) an aspect of a functional malefic planet afflicted by other(s) functional malefic planet,

5) more than one functional malefic planet at the same time.

Fairly strong planet: A planet which has at lest 70% power, is unafflicted and well placed, is considered as fairly strong planet. 

Mild affliction: An affliction to the extent of 25% or less to a strong or fairly strong planet or the most effective point of a non-mooltrikona sign house is considered as a mild affliction. 
LOSS OF STRENGTH BY PLANETS 
a) A planet will lose strength if its mooltrikona sign house is afflicted. The loss of strength can be judiciously adjusted proportionately to the extent of affliction and to the strength of the lord of the house. 

b) A weak planet placed in an afflicted house will lose strength 

c) An otherwise strong planet placed in a non mooltrikona sign afflicted house will lose strength. Such a planet may give good results in the first place and will cause setbacks later.

d) A closely afflicted weak planet will lose strength 

e) A closely afflicted otherwise strong planet will lose strength Such a planet will give good results in the first place and will cause setbacks later.

f) A planet becoming weak due to close combustion will lose strength if the Sun is a functional malefic planet. Where the Sun is a functional benefic and it causes combustion to another planet, the planet will become weak for the purpose of transit affliction. A combust planet in its sign of debilitation and placed in a malefic house will have only 10% power.

g) When planets are placed in the malefic houses, they generally lose strength by 50% besides suffering through the significations of the malefic house. The placement in the sixth house can involve the person in disputes, debts and can cause ill health. The placement in the eighth house can cause serious obstructions for the significations ruled by the planet. The placement in the twelfth house can cause expenses and losses for the significations of the planet.

h) When planets are placed in their signs of debilitation, they lose strength. When planets are placed in their signs of debilitation in birth chart and navamsa, they lose strength .

i) If in Rasi chart the planet is badly placed and at the same time debilitated in navamsa it would lose strength 

j) A badly placed planet in its sign of debilitation will lose its power by 75%. 

k) A planet debilitated in navamsa would lose power