The final moments of Eli culminate in a profound tragedy, where spiritual and national devastation physically overpower him. The true catalyst for his collapse is not the military defeat of the Israelites, nor even the tragic death of his own two sons, but rather the desecration of the holy. When the messenger reveals that the Ark of the Covenant has been captured, the news strikes a fatal blow. The Ark was the most precious thing in the world to Eli. The sheer shock and deep heartbreak of its capture completely overshadow his grief for his family and his nation [אברבנאל, מלבי״ם, רד״ק].
Overcome by this sudden shock, Eli falls backward from his seat toward the open gate or the path leading up to it [מצודת דוד, מצודת ציון, רד״ק]. Because the space behind him is wide open, there is nothing to catch him or break his fall [ביאור שטיינזלץ]. The sheer force of the impact breaks his neck [רש״י, רד״ק, מצודת ציון, ביאור שטיינזלץ]. The fatal severity of this injury is the result of a dangerous combination: tumbling from an elevated seat, the awkward backward angle of the drop, and his position high up near the gate [מלבי״ם].
Eli's immediate death is directly tied to his frail physical state. Advanced in years, his body has lost its flexibility and strength. Consequently, he is unable to brace himself or shift his weight to the side to soften the blow [מצודת דוד, ביאור שטיינזלץ]. Furthermore, his heavy build turns the momentum of the fall into a deadly impact [רד״ק, ביאור שטיינזלץ].
The forty years he spent judging the Israelites serve as more than just a historical timeline; they provide further context for his physical decline. Decades of leadership have entirely drained his life force [מלבי״ם]. The relentless toil and heavy burden of guiding the nation for four decades are precisely what caused his premature aging and physical heaviness in the first place [אברבנאל].
On a deeper, spiritual level, the specific manner of Eli's death serves as a cosmic rectification for a past soul. According to this perspective, Eli is the reincarnation of Aaron the High Priest. Dying from a severe fall that mirrors the punishment of stoning, at the exact moment the Ark of the Covenant is mentioned, is destined to repair the spiritual damage caused by Aaron's involvement in the sin of the Golden Calf [חומת אנך].