Retrograde planet becomes very powerful and gives good results akin to its exaltation state. Venus (R) is considered as very powerful planet. One should analyze the horoscope very carefully when a planet gets retrograde.
Some books classify retrograde as :
If a planet is retrograde and is exalted at the same time, it is considered as debilitated planet.
On the other hand, if a planet is retrograde and is debilitated at the same time, it is considered to be exalted planet.
However, in practical, the above statement does not hold true after anaylyzing many horoscopes.
E.g., in case of horoscope of Swami Ramkrishan Paramhansa, there was Saturn Exalted and Retrograde in his 9th house. As per above statement, that Saturn should have become debilitated and had given very bad results. But, on the contrary, he was a great Tapasvi and a saintly and spiritual person of highest degree, one can achieve in a life. That’s because Exalted Saturn on retrograde became more powerful to give good results.