In other words, being apart from original Kebiishi duty, they were summoned wearing Kyusen (Bow and arrow) that was forbidden for others except for military officers and military horses were supplied by Meryo during their duty.
つまり、本来その任にあたる検非違使とは別に、天皇から、武官以外には禁止されていた弓箭を帯びての招集を受け、その任務の間、馬寮より官馬が支給される。