I assume the English sentence is your own attempt at translation. It contains factual errors that make it impossible to understand what is happening.
"Stiel" is a short form for a Stielhandgranate. First, let's look at how it works:
The grenade mounted a charge head within a sheet-steel cylinder atop a long hollow-wooden handle. Internally, the explosive...was connected to a detonator, and a pull cord ran from the detonator down the length of the hollow handle, emerging from the base. To use it, a soldier would simply pull the string downwards...setting the fuse burning.
The hand grenades used by the Allied at the time (same as modern ones) have a security pin that has to be removed before triggering. It might be tempting to think of that as a "Stiel". But first, the German engineering term for such a pin is "(Sicherungs-)Stift", and secondly, the German grenades, as described, had no safeguard and were primed by pulling a cord.
The verb "abziehen" in Remarque's text describes the lighting of the fuse. Its use is a transference of the older technical term "Abzug", which is the manual trigger of a gun, to the newer weapon.
If the sentence could also be written as "die Stiele werden ihnen abgezogen und zugereicht", "ihnen" would be the soldiers and it would sound as if the grenades were initially part of the body of the soldiers, were removed and than handed back to them. That is obviously nonsense.
"abgezogen" is instead used as a predicate of the subject "die Stiele". In a longer form, the sentence could also read:
die Stiele werden ihnen in einem abgezogenen Zustand zugereicht.
which is also the form for which a direct English translation exists:
the grenades are handed to them in a triggered state.
or maybe shortened to
the grenades are handed to them already triggered.