A solitary warrior's stand can sometimes alter the entire course of a battle. In a fierce clash against the Philistines, Eleazar demonstrated extraordinary heroism by fighting entirely alone with fierce dedication. God brought about a massive victory through him, as he initiated the strike and saved the battlefield [מלבי״ם].
The sheer physical toll of this solo campaign was immense. Eleazar fought to the point of absolute exhaustion, his body drained from the endless, relentless swinging and striking of his weapon [מצודת ציון, מצודת דוד]. The intensity of the combat led to a severe physical reaction. The primary approach among commentators is that his hand suffered from intense muscle cramping and paralysis. Having gripped the weapon for so long, his hand lost its ability to open. His fingers remained locked in a clenched position, making it impossible to release his grip, so that his hand appeared as if it were permanently fused to the weapon [מצודת דוד, רלב״ג, ביאור שטיינזלץ]. An alternative perspective suggests that the sheer volume of blood from the battle physically glued his hand to the hilt, though the muscle paralysis explanation is generally considered more likely [רלב״ג].
The actions of the broader Israelite army during this event highlight the solitary nature of Eleazar's fight. Initially, the Israelite forces had fled from the Philistines in defeat. It was only after witnessing Eleazar's supreme, isolated bravery that they turned back and returned to the battlefield [רד״ק]. However, their return was not to offer military support. The commentators agree unanimously that Eleazar carried out the entirety of the combat and killing by himself, without any assistance. The rest of the people did not need to engage in the fight at all [רש״י, מצודת דוד, רד״ק]. Instead, they merely followed in his wake to strip the fallen enemies of their valuable clothing and belongings, acting solely as gatherers of the spoil [מצודת ציון, ביאור שטיינזלץ].