The velocity of planets: was i t/ is it taken into account by traditional astrologers?

I would guess in most traditions it was considered in some way. In Lillys work it was, at least(faster moving planet has stronger effect etc.).
At the end of the day, while not everyone would be taking fast/slow moving I think most approaches out there would count retrograde movement and that is also about apparent velocity one way or another...

Yes it is considered as accidental dignity respectively weakness. Like Saturn now, a stationary planet moving roward retrograde is seen as very weak. But I have to confess that I do not remember where and when this was written.

I found it now at Morin, Astrologia Gallica, book XXI, part 2, section 12 (printed 1661).

Thanks a lot! Interesting, didn't know that Morin took that into account.

It's quite a standard notion in ancient and medieval astrology that a planet being swift and direct in motion are conditions of strength, whereas being slow and retrograde are conditions of weakness (with the first station, moving into retrogression, being worse than the second). You will find it in many introductory texts.