So, I got a 4slot greater and trained it to 5 slots since there is no info on the wiki about what can be trained on greaters. Only thing trainable is magical abilities, increasing mag/combat skill caps, and stats. Mine gave me 1501 points to spend. Mines base damage was already capped.
Magical abilities-
-Chiv-500pts
-discordance-500pts
-poisoning-100pts
-Mysticism-500pts
-Spellweaving-500pts
-magery mastery-1pt
Magical abilities-
-Chiv-500pts
-discordance-500pts
-poisoning-100pts
-Mysticism-500pts
-Spellweaving-500pts
-magery mastery-1pt