Magistra explicat non solum hastam, sed etiam sagittam telum vocari posse.

Because Latin very often uses an indirect statement construction instead of a that-clause.

After verbs like say, think, know, show, or explain, Latin commonly uses:

• an accusative subject
• plus an infinitive

So here:

• Magistra explicat = The teacher explains
• non solum hastam, sed etiam sagittam telum vocari posse = the thing being explained

Literally, Latin says something like:

• The teacher explains not only a spear, but also an arrow, to be able to be called a weapon.

In normal English, of course, we turn that into The teacher explains that...

They are accusative because they are the subjects of the indirect statement.

In English, the subjects would be a spear and an arrow. But in Latin indirect statement, the subject is put in the accusative, not the nominative.

So:

• hasta = a spear
• hastam = a spear, as accusative subject of the infinitive
• sagitta = an arrow
• sagittam = an arrow, as accusative subject of the infinitive

This is one of the most important Latin patterns to get used to:

• accusative + infinitive for reported speech/thought/explanation.

Non solum ... sed etiam ... means not only ... but also ...

Here it connects hastam and sagittam:

• non solum hastam = not only a spear
• sed etiam sagittam = but also an arrow

So the contrast is between the two items. The teacher is explaining that the label telum applies not just to one of them, but to both.

Vocari is the present passive infinitive of vocare.

• vocare = to call
• vocari = to be called

So telum vocari means to be called a weapon.

That passive matters a lot. The sentence is not saying that the spear or arrow is calling something else a weapon. It is saying that the spear and arrow can be called a weapon.

Because posse means to be able, and it normally takes another infinitive.

So:

• vocari = to be called
• posse = to be able
• vocari posse = to be able to be called

In smoother English, that becomes:

• can be called

So the Latin uses two infinitives where English often uses a modal expression.

Because it is inside the indirect statement.

In a normal independent sentence, you might expect a finite verb such as potest or possunt. But once Latin puts an idea into indirect statement after explicat, the verb of that reported statement becomes an infinitive.

So instead of something like a finite can, Latin gives:

• vocari posse = to be able to be called

That is exactly what we expect in an accusative-and-infinitive construction.

Telum is the word that means weapon (or missile/weapon more generally), and it goes with vocari.

The pattern is:

• aliquid telum vocari = something to be called a weapon

So in this sentence:

• hastam telum vocari
• sagittam telum vocari

mean that a spear and an arrow can each be described by the word telum.

In other words, telum is not the object of explicat. It belongs with vocari.

Because with verbs like vocare (to call), the name or label can stand as a predicate accusative in this construction.

Compare the idea in English:

• They call the spear a weapon.

Here the spear and a weapon are both tied to the verb call.

In Latin indirect statement, that becomes:

• hastam telum vocari

So:

• hastam = the thing being called
• telum = what it is being called

Both appear in the accusative within this infinitive construction.

Because the sense is not only a spear, but also an arrow, can be called a weapon—that is, each one individually falls under the category weapon.

Latin is not saying they can be called weapons as a plural class label here. It is saying that each item may be described as a weapon.

So the singular telum is perfectly natural.

Because Magistra explicat forms a complete main clause:

• Magistra = the teacher
• explicat = explains

After that comes the content of the explanation, in indirect statement form:

• non solum hastam, sed etiam sagittam telum vocari posse

A very useful way to read it is:

1. Find the main verb: explicat
2. Notice the accusatives: hastam, sagittam
3. Look for the infinitives: vocari, posse
4. Recognize an indirect statement

That makes the structure much easier to understand.

Yes. Latin word order is much freer than English word order.

Putting posse at the end is natural Latin and gives a neat finish to the indirect statement. But Latin often moves words around for emphasis, balance, or style.

What matters most is not position alone, but the forms:

• hastam, sagittam, telum are accusative
• vocari, posse are infinitives
• Magistra is nominative
• explicat is the main finite verb

So even if the order changes, the grammar still shows how the sentence works.