portly > stately, magnificent; dignified, imposing

5 That one of the old heroes seems to be:

That > [So that] seems > [he seems]

6 He the Six Islands, comprovincial

the Six Islands > (Ireland, Iceland, Gotland, the Orkneys, Norway, Denmark) comprovincial > {Belonging to the same province}

7 In ancient times to Great Britain, 8 Shall to the same reduce, and to him call

reduce > bring back (Latin reducere)

9 Their sundry kings to do their homage several.

several > [individual, different; variously]

303.33