Sharpening knives on Erev Shabbos:
One is to beware to sharpen the [kitchen] knives every Erev Shabbos, as preparing oneself for eating is included within the honor of Shabbos. In addition [at times] one needs to sharpen the knives for the sake of Shalom Bayis [marital harmony], such as if the blade has dulled and one is unable to cut with it.
One should be careful to sharpen the knives on Erev Shabbos. This is done for honor of Shabbos and for purposes of shalom bayis.
 This is further hinted to in the words “And prepare Es/that which you brought” and a knife is alluded in the word “Es”, from the wording of “Lesim Ulemizmoros”. Thus implying in the verse that one is to prepare the knives before Shabbos. [ibid]
 This is learned from the verse “And you shall know that your tent is in harmony” and the Sages expounded this to be referring to the sharpening of a dull knife for the sake of Shalom Bayis. [Ibid]