Æstel is the word Alfred used in the prologue to his translation of Gregory’s Pastoral Care for objects which he sent out to his bishops, along with copies of the translation. In his mind, therefore, it had a very definite meaning: it was an object, and a valuable one; and he had no doubt that the word would be understood.
The word is now bandied about by archæologists, museum curators, auction houses (and various others in imitation) to refer to certain artefacts which have been dug up, displayed or put up for sale; but Anglo-Saxon linguists appear to agree that the word’s meaning is not totally clear.
In Alfred’s translation, æstel was glossed in the 12th/13th century, as both indicatorium and festuca: rather ironic, because Alfred’s reason for translating the work into Anglo-Saxon in the first place was that he found monks commonly had insufficient Latin to understand the original: now he was being glossed back into Latin as Anglo-Saxon had become the unfamiliar language.
The glosses (‘meanings’) are to aid understanding; they are not derivations. The often suggested origin is not Germanic at all, but Latin: a diminutive of hasta, a spear (hastula, hastella). This doesn’t fully explain why Alfred should send out small spears with his ‘book’.
Two lexical points to follow up:
a) the Latin glosses for æstel, added to the manuscript, indicatorium and festuca, need to be investigated. How are they – and were they – to be understood?
b) if æstel had a Latin origin (hastula/hastella), one would expect similar words to appear in other Romance languages, perhaps with something like the same meaning. And in any case, what textual evidence is there for the meaning of hastula/hastella?
Coincidentally, festuca, hastula, hastella are all current in scientific terminology – festuca is a type of grass; hastula a type of snail and a part of a palmate leaf; and hastella a genus of sticklike tropical insects.