[xuē tiě rú ní]   

削    铁    如    泥    切削铁器如同斩剁泥土一样。形容兵刃极其锋利。 褒义>

削铁如泥是对宝刀宝剑锋利度的一个夸张的形容，表示刀剑切削铁器像切泥一样的容易。形容兵刃极其锋利。

Would cut clean through iron as though it were mud

削铁无声    削足适履    削株掘根    削发披缁    削木为吏