Breakdown of Il a besoin de quelque chose de robuste comme l'armure de fer.
il
he
de
of / from / any (in negative sentences) / about (concerning)
avoir besoin de
to need
comme
like, as
Questions & Answers about Il a besoin de quelque chose de robuste comme l'armure de fer.
Why is there a de before robuste?
When you modify indefinite pronouns like quelque chose (something), rien (nothing), quelqu'un (someone), or personne (no one) with an adjective, you must place de between the pronoun and the adjective. So, "something sturdy" becomes quelque chose de robuste.
The word chose is feminine, so shouldn't the adjective after it be feminine?
While the standalone noun une chose is feminine, the indefinite pronoun quelque chose always takes a masculine singular adjective. In this sentence, robuste looks the same in both genders because it ends in an "e", but if you used "heavy" (lourd), it would strictly have to be quelque chose de lourd, not lourde.
Is it correct to have two des so close together in besoin de quelque chose de?
Yes, it is perfectly correct and necessary here. The first de is part of the fixed expression avoir besoin de (to need). The second de is required by the rule connecting quelque chose to its adjective. Each de serves a separate, required grammatical purpose and you cannot drop either of them.
Could you say l'armure en fer instead of l'armure de fer?