Green’s Dictionary of Slang

a mild oath, lit. ‘God’s light!’.

1599		Jonson Every Man Out of his Humour II i: ’Slight, our presence has cut off the convoy of the jest.
1605		Chapman & Jonson Eastward Ho! II iii: ’Slight, how thou terrifiest me!
1609		Jonson Silent Woman IV v: ’Slight, let him rage.
1610		Jonson Alchemist I i: Where’s your judgment? S’light, / Have yet, some care of me.
1614		Jonson Bartholomew Fair II vi: ’Slight, he will call company, you shall see.
1623		Massinger Bondman II ii: ’Slight shee’s asleepe!
1636		W. Davenant Wits II i: ’Slight, see how she stands!
1652		Jonson, Fletcher & Middleton Widdow I ii: A Pox ont, have I found it? ’slight away with’t with all speed man.