technically, if you put it this way, almost all special characters are just beefed up normal commanders with special rules.
Sure there are some exceptions such as Avatar and Daemon Prince.
But arent all Space Marines are the same? Some are just more excellent and become commanders/captains and if they continue they become leaders of the chapter.
Yes I agree Belial is a bit bland, lacks in fluff, doesnt have much taste to him and bit more expensive than he should be.
Lets dissect him.
Belial comes with TDA, AP3 fleshbane sword and can be switched to TH/SS or 2 Lightning Claws for free, also a free Teleport Homer.
7 Special rules out of them 3 rules are unique to him;
- Tactical Precision (No Scatter for DS),
- Grand Master of Deathwing (Deathwing Terminators are troops),
- Marked for Retribution(precision shots on 5+), and also has The Hunt as a Warlord Trait.
Total 190 PTs
Now a DA Company Master in Terminator Armor with SB/PS costs 130 points. Cant have Lightning Claws, or TH/SS, but can take Special Issue Wargear and Chapter Relics which compensates for that. Has an identical stat line. With Relic of Unforgiven and Mace of Redemption he costs 175 points and the mace is much better than the Sword of Silence Belial comes with.
The only thing that makes him special are the 3 rules. Marked for Retribution is useless since most ppl run him with TH/SS and he is not a shoty character.
Now that leaves me questioning how would you actually make him unique and useful?
In DA book the most unique HQ would be Azrael due to assortment of Special rules and Wargear, however he is expensive and I never actually found him useful.