There is another account of Lord Shani’s involvement in Mahabharat . In Shani Mahatmya , Lord Shani while speaking to Kali Yugan King Vikramadiyaa tells him that did not spared even Lord Krishna.
When Lord Shani entered in horoscope of Lord Krishna. People blamed Lord Krishna for stealing Syamantak Mani and killing Satrajit , when Lord Krishna realized this he worshipped Shanidev , he  removed his gaze and asked Lord Krishna that he will come out of the false allegations.
Lord Krishna asked Shani  that in upcoming great war between Kauravas and Pandavas which is the side that  upholds dharma  at this Shani replied “Pandavas”. Lord Krishna requested him to favour Pandavs . Shani has given an interesting reply ” I and Yama are two judges. I deliver fruit of ones’ deeds through ones’ life through the punishment and rewards while Yama grants fruit of one’s deeds after death. Since am living curse of my mother in my human incarnation  and my human incarnation is great friends with Duryodhana , I am  governed by  laws of karma so I can’t influence the outcome of war directly or indirectly  as my human incarnation has to take part in the war but as you are supreme lord I cannot deny your request and hence I am in crisis , whether to follow the duty or deny the request of lord. Since you are Ultimate Lord , please free me from this crisis situation”

Lord Krishna smiled at this  and replied Shani that he will get him liberated from  crisis and also ensure that his amshavatara attains salvation.