I got around to listening to the life of Sinuhe and when the narrator (Sinuhe?) is telling about the new king he says "he's vengeful, a smasher of foreheads". That's oddly specific. Is that just a phrase - something that emphasises strengh? Does it have any cultural meaning? Is smashing foreheads seen as extra terrible? This just jumped out to me so I was wondering ^^

‘smasher of heads’ (line 55) comes after a long section wherein Sinuhe laments the loss of the King when speaking to another. In this section he talks about how good the new King will be at ruling Egypt, and then starts listing things like 'He is the possessor of Wisdom’ or 'It was he who subjugated the foreign lands while his father was in the palace’. 'Smasher of heads’ is a very specific royal propagandistic image of strength that you see turn up in many battle reliefs, wherein the King is shown holding the hair of multiple enemies in one hand and a mace in the other:

In one way this demonstrates the power of the King over his enemies, and on the other it falls in line with Ma'at, wherein images are said to be imbued with Heka and whatever they depict could come to fruition. By showing the enemies in the defeated position the Egyptians believed that it was more likely for their enemies to be defeated to 'balance’ Ma'at. This royal image goes all the way back to the Early Dynastic period with the Narmer palette:

So this motif is one invoked again and again, so much so that it would be common knowledge for the Egyptians listening to the tale. Interestingly, the literal translation of the line is 'one who is vengeful, one who splits open the top of heads’ which is much more gruesome than 'one who smashes foreheads’!