2 Samuel 20:8

20:8 When they were near the big rock that is in Gibeon, Amasa came to them. Now Joab was dressed in military attire and had a dagger in its sheath belted to his waist. When he advanced, it fell out. ¹ 

2 Samuel 23:21

23:21 He also killed an impressive-looking Egyptian. ²  The Egyptian wielded a spear, while Benaiah attacked ³  him with a club. He grabbed the spear out of the Egyptian’s hand and killed him with his own spear.

[20:8]  ¹ sn The significance of the statement it fell out here is unclear. If the dagger fell out of its sheath before Joab got to Amasa, how then did he kill him? Josephus, Ant. 7.11.7 (7.284), suggested that as Joab approached Amasa he deliberately caused the dagger to fall to the ground at an opportune moment as though by accident. When he bent over and picked it up, he then stabbed Amasa with it. Others have tried to make a case for thinking that two swords are referred to – the one that fell out and another that Joab kept concealed until the last moment. But nothing in the text clearly supports this view. Perhaps Josephus’ understanding is best, but it is by no means obvious in the text either.

[23:21]  ² tc The translation follows the Qere and many medieval Hebrew mss in reading אִישׁ (’ish, “man”) rather than the Kethib of the MT, אֲשֶׁר (’asher, “who”).

[23:21]  ³ tn Heb “and he went down to.”