Mægen-fæst

According to the Old English Dictionary:

mægen-fæst

adj. Strong, vigorous, firm:--Sealde him snyttru mægenfæste gemynd he gave him wisdom, vigorous thought, Exon. 39 b; Th. 130, 28; Gú. 445. Ǽlc líchamlíce gesceaft ðe eorþe ácenþ is fulre and mægenfæstre on fullum mónan ðonne on gewanedum every bodily creature that earth produces is more complete and more vigorous at the full moon than when the moon has waned, Homl. Th. i. 102, 21. [Cf. mægen-leás.] mægen-fæst