Alignment is actually the D&D alignments (Lawful/Chaotic Good/Evil, with Neutral in between) with 'Mad' replacing the moral component if Mad Enhancement shows up.

Ah, right, [url=http://www.pastebin.com/TZFU8khQ]something I wrote[/url] after I got tired of seeing arguments about OC power levels and situations where random nobodies had abilities that would let them curbstomp anyone less than Gilgamesh.

[quote=Grey]
...I just realized I still have no idea what the Mana/Magical energy stat for Servants actually does.
[/quote]

Magical energy the Servant generates. It's... weird. Actual mana storage is independent (i.e., Gilgamesh as of F/SN has effectively infinite mana as he has a decade-long stockpile fuelled by orphans, though his stat in it is the same as ever).