The Egyptian had in his hand a spear like a WEAVER's BEAM

[TonyChanYT]

2 Samuel 21:

19 And there was again war with the Philistines at Gob, and Elhanan the son of Jaare-oregim, the Bethlehemite, struck down Goliath the Gittite, the shaft of whose spear was like a weaver’s beam.

1 Chronicles 11:

23 And he struck down an Egyptian, a man of great stature, five cubits tall. The Egyptian had in his hand a spear like a weaver’s beam, but Benaiah went down to him with a staff and snatched the spear out of the Egyptian’s hand and killed him with his own spear.

What was so intimidating about a spear like a weaver's beam?

Let's check a parallel account in (Brenton Septuagint Translation) 2 Samuel 23:

21 [Benaiah] smote an Egyptian, a wonderful man, and in the hand of the Egyptian was a spear as the side of a ladder; and he went down to him with a staff, and snatched the spear from the Egyptian's hand, and slew him with his own spear.

It was thick.

More details at David vs Goliath in 1 Samuel 17:

7 The shaft of his spear was like a weaver’s beam, and his spear’s head weighed six hundred shekels of iron. And his shield-bearer went before him.

It was threatening indeed.