suffragan

suffragaani A bishop seen in relation to his archbishop or metropolitan province (which may summon him for support, to attend synods etc.).
(RQ:Mlry MrtDrthr):

Now take your hors said sir Tristram And as ye say / soo hit shal be / and alle thyn euylle wil god forgyue it yow and I doo / And here within this myle is the suffrecan of Carleil that shalle gyue yow the sacrament of baptym

A suffragan could share the tasks which were special to bishops; for example, by conducting confirmations.