sea-nymph > (See 304.19:3 ff.) hight > called

2 Of my dear dame is loved dearly well;

Of > By dame > lady

3 In other none, but him she sets delight,

In other none, but him > [In no one else but him]

4 All her delight is set on Marinell; 5 But he sets naught at all by Florimell: 6 For ladies' love his mother long ago 7 Did him, they say, forewarn through sacred spell.

forewarn > ?give warning of (see 304.25-6; this use is not in OED) sacred > {Holy by association with a god (i.e. Proteus); also: accursed, after Latin sacer} spell > discourse, talk; hence: prophecy

8 But fame now flies that of a foreign foe

fame > report, rumour (Latin fama) of > by

9 He is slain, which is the ground of all our woe.