Ethica's suggestion of a 7 Move seems reasonable. It is the most likely outcome of rolling the movement dice. Compare it to other fixed moves available in the official game:
Mercenaries from the Barbarian Quest Pack and the
[British
-edit] Wizards of Morcar expansion have the following move values and defend dice:
Crossbowman, Halberdier ... Move 6 / Defend 3
Scout ... Move 9 / Defend 3
[Swordsman WoM...Move 5 / Defend 5
-edit];
Swordsman BQP... Move 5 / Defend 4Elves from the Elf Quest Pack have the following move values and defend dice:
Elven Archer ... Move 6 / Defend 2
Elven Warrior ... Move 6 / Defend 3
High Alchemist ... Move 8 / Defend 3
Necromancer ... Move 8 / Defend 4
Archmage ... Move 8 / Defend 4
Sorcerers from Against the Ogre Horde have the following move values and defend dice:
apprentice Chaos Sorcerer ... Move 8 / Defend 4
Chaos Sorcerer ... Move 6 / Defend 5
Chaos Mage ... Move 6 / Defend 4
Sorcerers from the Wizards of Morcar expansion have the following move values and defend dice:
High Mage ... Move 5 / Defend 5
Necromancer ... Move 6 / Defend 6
Storm Master ... Move 7 / Defend 5
Orc Shaman ... Move 7 / Defend 5
Sorcerers and named Orcs from the game system Quest Book have the following move values and defend dice:
Fire Mage ... Move 8 / Defend 5
Witch Lord ... Move 10 / Defend 6
Ulag ... Move 10 / Defend 5
Grak ... Move 8 / Defend 4
Named monsters and Orcs from Kellar's Keep have the following move values and defend dice:
Dwarven Kings Skeletons ... Move 6 / Defend 4
Gragor, Ograk, and Borokk ... Move 7 / Defend 4
Named monsters from Return of the Witch Lord have the following move values and defend dice:
Skulmar ... Move 8 / Defend 6
Doomguard ... Move 8 / Defend 6
Witch Queen ... Move 6 / Defend 6
Witch Lord ... Move 10 / Defend 6
I included the Defend values as they relate to fixed movement. Note that named figures probably have higher Defend dice to compensate for rolling black shields. Another factor seems to be the class of the figure, as a Mercenary Scout moves 1 square faster than the fastest mortal mage. Gravaillon's modifiers for Hero movement could also apply here.
The maximum fixed movement allowance is 10. I'd say that would apply to humans elves as well. A human or elf has a starting move of 8 or 9, depending on training. Plate Mail lessens this to a Move of 4 or 5, as evidenced by the Mercenary Swordsman. This halving of a starting move also parallels the Plate Mail rule of halving the movement dice.
The addition of smaller armor (Helmet, Shield, or Bracers) appears to reduce fixed movement by 1 square. A Helmet (and possibly a shield) don't reduce movement if combined with Plate Mail, as shown by the Mercenary Swordsman (but this may also be attributed to class).
Chain Mail is more problematic, as it seems to not always be accounted for in the Defend value of many figures. Elves wear it, but have only 2 black Defend dice, or 3 with a Shield. Orcs also wear it and have only 2 black shields to defend with, as well (unless named).
This may be explained by Elves and other less-than-Hero-status monsters as starting out with only 1 Defend die. -edit Mercenaries ambiguously either wear Chain Mail or Plate Mail. Taking all that into account, and considering class, I'd say Chain Mail reduces the movement of a figure by 2 or 3 squares.
Would it be worthwhile to apply these observations to a Hero's movement, rather than going with an average Move 7?