Literally: vessel – use – poverty – scarcity
Alternately: Someone gifted with relatively good across-the-board skills… who, because of this, fails to develop any one skill to its full extend and ends up doing things only halfway. A “Jack of all trades but master of none.”
Alternately, someone of great ability who ends up being highly valued – and used – by those around them, who accordingly fails to achieve any significant successes or receive recognition for their work. This latter meaning may be signified by adding 人宝 (hitodakara), literally “human treasure,” to the phrase.
Notes: On its own, 器用 is a set phrase meaning “skillful,” “dexterous,” etc.