Does bajutsu 馬術 refer to the use of weapons on horseback, or less specifically the art of the horse riding and horsemanship?
I'm trying to work out if bajutsu is the horse equivalent to kyūjutsu 弓術, kenjutsu 剣術 and sōjutsu 槍術.
My dictionary (imiwa on iOS, which I believe inherits from one of the online standard dictionaries) lists 馬術 as the English "equestrian". Meaning, the answer would be the latter of your 2 suppositions.
As I understand it from Japanese Wikipedia 馬術 article, it means equestrianism nowadays, but until 1871, only samurai were allowed to train it, and it belonged to the 武芸十八般 (bugei juuhappan), the 18 martial arts originating in China, of which 弓術 (kyuujutsu), 剣術 (kenjutsu) ... also were a part.