Is there a difference in using a Sharp knife on Shabbos to cut Challah…. is there a difference between a serrated knife (saw knife) or a regular knife? both cut the challah? and what is the reason for the Halacha Pesak?? can you please quote sources?
The Rema brings that one should sharpen his knife on erev Shabbos. One of the reasons given for this is because if the knife is dull it can be frustrating to cut things with it, and it can cause fights- something we want to avoid especially on Shabbos. There are people that are careful to cut their challah on Shabbos with a smooth knife so it will not make too many crumbs. This is because crumbs that fall on the floor and are stepped on can cause one to become poor and for kabalistic reasons.
Rema O:Ch 250-1, M:B 250-5, Piskei Teshuvos 250-4.