As the name says he is the holder of danda. Danda means staff and this staff is used to serve the justice. So, Dandapani swamy is the one who serves with the justice to these devotees then and there.

Worshipping this swamy on Tuesday with turmeric will help one get his manglik  dosha Pacified. Though in general it is said Lord Murugar is the atipati for Mars; in specific Dandapani Swamy is the one. So, the one with manglik dosha in his horoscope has to worship this swamy on Tuesdays all over his life for getting married & to sustain his married life. As he is the Lord of justice, worshipping him on Tuesdays during  Mars hora will help one win legal battles & also enemies. 

On every shuklapaksha Shashti (6th day from Amavasya), Dandapani Puja will happen for the success of every step one takes forth. And, on every Krshnapaksha Shashti (6th day from Pournami), Vishesha Shaktivel Puja along with the Vignahara Kartikeyar & Aghora Subrahmanya Puja will happen for one to get his kuja dosham pacified for the happy married life and also for the subjugation of enemies.