None of the weapon expertise stack, though you do get the bonuses from a shield on your back if you are fighting unarmed.

Single Handed is slightly faster than one handed and shield, but lacks the (small) defensive bonus and opportunity for bonuses and enchantments on the shield. The skill details, from the Dragon Knight Saga FAQ/Guide:
SINGLE-HANDED WEAPON EXPERTISE: This affects fighting when you have a single one-handed melee weapon equipped, leaving your other melee slot vacant. This has an advantage in swinging speed, but its power if extremely low compared to other weapon expertise skills. This is possibly the worst possible choice to make, aside from Unarmed. One point is permanently invested by default.

Code
 Passive skill

Stats        1     2     3     4     5     6     7     8     9     10
---------------------------------------------------------------------------
Damage bonus 2%    5%    9%    12%   15%   19%   22%   25%   29%   34%

11    12    13    14    15
--------------------------------
34%   35%   36%   36%   37%    Damage bonus

NOTE: Skill levels marked with * are only available for new characters started at the FoV chapter and put at least 12 skill points into the skill during character creation. Characters started in ED can only reach level 13.




SWORD AND SHIELD EXPERTISE: This affects fighting when you have a one-handed weapon and a shield equipped. This is a decent skill that gives a good damage bonus for the cost of some of Single-Handed Weapon's speed, but the bonus to the shield is negligible, and doesn't affect enchantment-based bonuses. This
is your only option for using a shield, but consider Dual-Wield or Two-Handed instead. One point is permanently invested by default.

Code
Passive skill

Stats        1     2     3     4     5     6     7     8     9     10
---------------------------------------------------------------------------
Damage bonus 0     7%    14%   21%   28%   35%   42%   49%   56%   63%
Shield bonus 5%    8%    11%   14%   17%   20%   23%   26%   29%   32%

11    12    13    14    15
--------------------------------
70%   77%   84%   91%   98%    Damage bonus
34%   36%   38%   40%   42%    Shield bonus

NOTE: Skill levels marked with * are only available for new characters started at the FoV chapter and put at least 12 skill points into the skill during character creation. Characters started in ED can only reach level 13.