You've got a couple of options, melee, or shooty.
If you don't have any other fast attack I suggest breaking the squad into two separate fast attack choices (2x five man squads) each with 2x Meltaguns. The nice thing about Blood Angels Assault Squads is that you can have two special weapons in a 5 man squad, not one per 5 models like other Marine squads.
You can give your Sergeant a pair of Inferno Pistols (That he can shoot both of thanks to Gunslinger) for 30 points total, or some other pistol combo (Grav Pistol + Inferno Pistol, Plasma Pistol + Grav Pistol, whatever you fancy).
Or
You can try to keep it somewhat cheaper and just give the Sergeant a Power Weapon + Bolt Pistol. A power axe is cool but sadly he'll likely get taken out in a challenge unless he's fighting another model with an unwieldy weapon. My personal preference is a good old power sword for the at initiative
AP:3 swings, or conversely a Power Mace for
ST:7 attacks on the charge (
ST:4+ 2 for the mace, +1 for furious charge) at initiative. Sadly it's at
AP:4, however. Of the three options I like the sword the most. It's also fairly cheap, and you can tack on melta bombs as well if you want to.
In theory you could run one squad with a melee sergeant and one squad with a dual inferno pistol sergeant, each squad sporting two melta guns plus two
BP &
CCW troopers.
Either way, they'll be good for dropping in and doing some damage to an armored target, with the 4x melta shot (2x from the squad, 2x from the Sergeant's pistols) squad being the best option for that end of course.
Hopefully that helps. Take it easy for now & best of luck.
-Red__Thirst-