Translation:The knight had to abandon his sword.
I'm not entirely sure if this is relevant, but according to the tips and notes, for subject to pre-verbal object, the pre-verbal nominal must be in the dative/genitive case. In this case, always the genitive. The dative is used when the following word begins with a vowel; the genitive is used otherwise. For example:
Azantys dāri rijas. "The knight praises the king." Dāri rijagon azanto bēvilza. "The knight must* praise the king." The last sentence might also be translated "The knight has to praise the king."
Hope that helps!