Learn Portuguese (Portugal): Preciso de uma esferográfica para assinar.

While caneta is the general term for a pen, esferográfica specifically means a ballpoint pen. In Portugal, it is extremely common in daily life to ask specifically for an esferográfica rather than a caneta when you need a standard pen to sign documents.

I see de after preciso. Is this preposition always mandatory with the verb precisar?

It is mandatory when followed by a noun or pronoun, as in this sentence with uma esferográfica. However, when precisar is followed directly by a verb, the de is frequently dropped in spoken European Portuguese. For example, if you just wanted to say you needed to sign, both preciso de assinar and preciso assinar would be correct.

Could I say para eu assinar instead of just para assinar at the end of the sentence?

Yes, you could. Since the person needing the pen and the person signing are the same, the standard impersonal infinitive assinar is the most natural choice. However, using the personal infinitive para eu assinar is also grammatically correct and is sometimes used for extra clarity, translating literally as for me to sign.

Why does esferográfica have a written accent mark?