Ful-lǽst

According to the Old English Dictionary:

-lést, -láste (?) es;

ful-lǽst

m. Help, aid, support; auxĭlium, subsĭdium :-- Is mægenwísa trum, fullésta mǽst, se ðas fare lǽdeþ he is a firm army-leader, the greatest of supports, who leads this expedition, Cd. 170; Th. 213, 18; Exod. 554. Ðæt we hæfdon æt ðæm fýre leóht and fulláste that we might have light and help from the fire, Nar. 13, 3. [O. Sax. fullésti; O. H. Ger. folleist.] ful-læst