“Finnis”, as suggested earlier, should probably be spelled “finis” and translated as boundary, limit, border; summit, end; object, aim.
“Fatalis” is relating to destiny or fate; fated, destined by fate or deadly, fatal.
“Spei” would be the genitive or possessive case of the word spe (meaning hope), translated of hope.
My translation, therefore, would be:
The deadly limit of hope
All specific definitions are from http://archives.nd.edu/latgramm.htm