sure (adj.) 4
loyal, trustworthy, steadfast
1H4 III.i.1 [Mortimer to all] These promises are fair, the parties sure, / And our Induction full of prosperous hope
Cor I.i.170 [Martius to Citizens] You are no surer, no, / Than is the coal of fire upon the ice
Cym I.vii.139 [Iachimo to Innogen] I ... will continue fast to your affection, / Still close as sure
MA I.iii.63 [Don John to Borachio and Conrade] You are both sure, and will assist me?