दृढतरनिबद्धमुष्ठेः कोषनिषण्णस्य सहज-मलिनस्य।
कृपणस्य कृपाणस्य च केवलम् आकारतो भेदः॥
dṛḍhataranibaddhamuṣṭheḥ koṣaniṣaṇṇasya sahaja-malinasya|
kṛpaṇasya kṛpāṇasya ca kevalam ākārato bhedaḥ||
Krupana- miser and krupaana -knife differ from each other by merely an aa kaaram. They are same in nature.The knife must be held tightly by the fist. The miser is indeed tight fisted. The knife is held in its sheath (kosha).The miser clings on to his kosha (treasury). As the knife is made of iron it is black in nature.The miser too, to save the cost of washing clothes, is always badly dressed.
[Thanks to Mohan Ramiah]