I'll reply in more detail, considering everything is new to you. I'm not an expert but there are a few things I'd consider.
The Master on Cold OneWhat is wrong- I would not give him the Cloak of Twilight. Although it is a fun item, it's fairly expensive and expertly suited for a lone model, like a Master or Dreadlord on pegasus. While the character is in a unit, the cloak's save will only help in a few occasions. Shooting and magic tends to be distributed as shooting. A cannonball grants a "sir look out" roll if the character is mounted on a horse or cold one, and (s)he is in a cavalry unit. Only if this roll is failed, does the cloak show its worth. Once the character is in close combat, the cloak won't offer protection.
- The Gambler's Armour and Spellshield can not be combined, as both are magical armour.
- The point allowance for magic items is 50 points for a Master. You took 100 points. If you want 100 points of magic items, you need a Dreadlord.
OffenseIf we want to boost the offensive abilities of a Master or Dreadlord, there are plenty of options:
- Great Weapon: terrific choice, but you lose the rerolls to hit. This is a good way to make the character very solid against a diverse set of enemies, but there's a risk of missing many attacks. Required 2 hands, so can't be combined with a shield in combat.
- Halberd: not a bad choice, but the character stays stuck at S5. This means it's strong against most infantry and some monsters, but weaker against some of the toughest opponents. Requires 2 hands, so can't be combined with a shield.
- Lance: excellent in combination with a shield, but it does make the character a one-hit wonder. This combines well with the Cloak of Twilight or a cavalry unit. Keep in mind the performance will degrade rapidly after the charge.
- Sword of Anti-Heroes: cheap and very useful to take on some of those units with multiple characters. Can be combined with a shield. Popular to combine it with the Other Trickster Shard to make the character effective against heroes
- Sword of Might, Ogre Blade and Giant Blade: they are interesting because they combine with a shield but usually people prefer to save the points for a defensive kit.
DefenseYou'll want to defend your Master against incoming attacks. There are many ways to do it.
- Dawnstone: one of the best choices, cost-value, for a character with a 1+ armour save. Imagine taking a Strength 5 hit, then you get an armour save of 3+ and a 3+ reroll which beats any ward save you can get.
- Talisman of Endurance and Talisman of Preservation: if you want a ward save, most people go all the way and go for the 4+ armour save. It's a solid choice but leaves out little points for an offensive kit.
- Cloak of Twilight: rule of thumb is to put it on a character with a pegasus mount
- Charmed shield: for a cheap Master, this is usually an excellent choice to give him that extra life saver. Some people would put it on a pegasus, to force the enemy to waste a shot at the pegasus. Personally, I'd rather use it in combat, to make sure one very valuable attack gets blocked.
Choice of mountYou put the character on a Cold One. I assume the reason is fluff and the model.
In my experience (well, from reading people's army lists) it's always a choice between putting the Master on a Dark Steed or a Cold One. The Cold One gives the Master an extra armour save, and a slightly stronger mount. The Dark Steed makes the Master faster (M9) and fast cavalry. This means he can join a unit of Dark Riders or Warlocks and the whole unit can still move as swiftly as before.
However, when the character is on a Cold One, putting the character in a unit of Dark Riders or Warlocks makes the whole unit move at M7, test for stupidity and it loses the fast cavalry rule.
So, there are quite a few reasons to favour the Dark Steed, which doesn't prohibit the character from joining cold ones at all. There is 1 notable advantage of the Cold One: it gives 1 extra armour save +2 compared to the Dark Steed which only gives +1.
This means that, if the character wears heavy armour and a sea dragon cloak, the character already has a 1+ armour save with the cold one. It doesn't need a shield. A character on a Dark Steed would need another item (helm or shield) to give it a 1+ armour save.
Then there is the pegasus, which is one of the best mounts around if you want a flying character. It comes at a price though: the character loses the "sir look out" rule. This usually means that the character needs a good ward save against ranged attacks (Cloak of Twilight, Talisman of Preservation).
A few builds- Master, Dark Steed, Heavy Armour, Sea Dragon Cloak, Charmed Shield, Sword of Anti-Heroes, Other Trickster Shard
- Master, Dark Steed, Heavy Armour, Sea Dragon Cloak, Dragonhelm, Greatsword, Dawnstone
- Master, Cold One, Heavy Armour, Sea Dragon Cloak, Great Weapon, dawnstone, Ironcurse Icon
- Master, Cold One, Heavy Armour, Sea Dragon Cloak, Great Weapon, Talisman of Preservation
- Master, Pegasus, Heavy Armour, Sea Dragon Cloak, Shield, Lance, Cloak of Twilight
...
Sorceress level 2The Dispel Scroll is a near must item
Personally, I prefer to have at least 3 spells in a game. If you want a third spell, you can give the Sorceress the Ruby Ring of Ruin. It's not terrific, but in a small game that's actually a handy extra
BleakswordsThey are not my preferred unit, for they lack damage. But give them a shot and see how you like them!
DarkshardsI would give them the musician only. The musician helps for swift reforms and to break ties in combat resolution. Keep in mind that, at only 10 big, they aren't a very solid backup for the Sorceress.
An interesting option is to give them banner of eternal flame. However, some units in both Dwarfs and High Elves, have 2+ ward saves against flaming attacks... So it's a risky bet considering your opponents.
Dark RidersI would remove the champion and banner. Dark Riders are typically used for hunting small units, and baiting/fleeing. The banner could actually give away points to the enemy. That said, it's not a crime to have it... It might just turn the tide a few times!
Cold OnesExcellent choice. I would consider giving them a magic banner:
- Gleaming Pennant, if you don't have a Battle Standard Bearer. This helps them pass their stupidity as well.
- Standard of Discipline. This is always a good banner for the unit carrying a leadership 9 general. The unit already has the General's leadership, and can boost the general to Ld 10 for the benefit of other units. In this case, if the general leaves the unit, it's not a problem since the unit already has maximum leadership.
- Banner of Swiftness, which really helps the Cold Ones to cross the board quicker.
- Razor Standard really boosts the performance of the unit, but I consider a 5-big unit a bit small for such an expensive banner.