The correct answer is swords.
The Anglo-Saxons frequently used kennings in their work. A kenning is a mini riddle, usually hyphenated, that was used to describe something. For example, the kenning "she-wolf" was used to describe Grendel's mother, as it highlights her ferocity.
Here, the kenning "battle-shaft" is used to describe their swords, which must wait to be used until the deliberations have finished. This is an appropriate kenning for a sword because swords (a) are used in battle and (b) are long and narrow.