You can do this with the Developer Console. Open it and enter: exec respec=stats

Note: You can also use "powers" and "xp" in place of "stats" with respec.

But you still can't get the underworld armour - you need 30 of each stat, which is impossible.

You don't need 30 in each stat to equip a full set. The only thing you can't do is use all three weapons. Here's a breakdown:

• The player can have a total of 104 stat points (5 per level * 20 levels, plus 1 point for each stat)
• The most Defense required is 28, which leaves 76 points
• The armor requires Physical/Mental/Offense of 14/15/16 respectivly, so subtract 45. That leaves 31 points.
• Each weapon requires 30 points in one of Physical/Mental/Offense, but the player is only intended to use one of these based on their build. On top of the armor requirements, the most points needed here would be 16 (30-14), so we subtract that. This leaves 15 points (3 levels) of wiggle room.