Sentence:  Come thick Night, / And pall thee in the dunneſt ſmoake of Hell, / That my <WSD>keene</WSD> Knife ſee not the Wound it makes, / Nor Heauen peepe through the Blanket of the darke, / To cry, hold, hold. 
Meaning of the word marked with <WSD> tags:  Having a fine edge or point; sharp.