The Grand Master, the ultimate example of honour, purity and an example of one of the most outstanding warriors not just of the Grey Knights chapter but the entire Imperium.
But what is the best load out for this master of combat? That’s what we’re going to discuss here…
So the Grand Master weighs in at 175 points, for this you get a fantastic stat line by any space marine player’s standards, Terminator armour a storm bolter, Nemesis force sword, a cacophony of grenades, and Iron Halo…Not to mention his psyker level 1 status with 2 psychic powers to choose from and the biggest draw for most Grey Knight players the Grand Strategy special rule…
So I suppose we can forgive GW for giving us a slightly less comprehensive list of alternatives and upgrades for this character, but nonetheless there are still some items here for a Grey Knight player to get excited about:
Options available;
Upgrade to mastery level 2 – Not worth the cost as only access to 2 powers.
Swap storm bolter with:                          
Incinerator – Limited range, no access to Psyflame ammo.
Psilencer – Not powerful enough for points cost.
Psycannon – Great and very powerful but beware points cost
Swap Nemesis force sword with:         
Nemesis force Halberd – Why? You’re at I5 already, sword gives 3++ in CC
Pair of Nemesis force Falchions – Good for points if you’re going all out CC
Nemesis warding stave – Again over priced when sword gives 3++ in CC
Take up to 3 servo-skulls – Take if you’re DS’ing or using scatter weapons
Blind grenades – Cool for 5 points
Meltabombs – If you have 5 points sure
Digital weapons – Good value, take if you have 5 points spare
Psybolt ammunition – Take! Take! Take!
Empyrean Brain Mines – Nice idea good if playing low Initiative armies
Psychotroke Grenades – Great for a bit of random fun!
Rad Grenades – Good but costly…take if going all out CC
Orbital strike relay: – OK value considering you access all strike types
Barrage Bomb – Great against horde armies…
Lance Strike – Good for Mechanised armies
Psyk-out Bomb – Great for other psyker packed armies
Master craft any of his weapons – Take it on Psycannon if going gunline GK
Ok so that’s your options explained in a nutshell, but what about that Grand Strategy the Grand Master has? This ability is broken down into 4 options conveying different abilities on your units:
Hammer of Righteousness – Re-roll all to wound rolls of a 1
Shield of Blades – Gain counter attack
Spear of Light – Gain scout ability
Unyielding Anvil – Claim objectives as troops

How you decide to use these different abilities depends purely on what you plan to do during the game, if you’re running all troops that are deep striking you may want to consider shield of blades to cover yourself should you get charged…maybe your paranoid about your rolling, if so take Hammer of Righteousness.  
Now lets discuss some details of the finer points of what is the best all round load out for this sucka…on the 1 hand we want to accentuate his badass nature but more importantly we need to balance this with keeping him efficient for his points cost.

The best way to do this is to decide what exactly you want his role to be within your force and how he will arrive during battle…
So your Grand master can come into play 1 of the 5 following ways:
Teleportation
Stormraven
1 of the Land raider variants
Inquisitorial Chimera
Walking on foot
Whichever of these options you choose you should always have him with a unit and try to get him as near the action as you can…read his stats and you soon realise this guy is a CC monster with excellent shooting skills.
That in mind here are a couple of suggested load-outs and the reasons behind the choosing them:
Grand Master 1: 235pts
Psycannon, M/Crafted.
Blind grenades.
Digital weapons
This load out is perfect if you fancy a gunline of Grey Knights, stick him in a combat squad of 5 termies with 2 Psycannons so you have a hardcore firing line of 3 Psycannons, stick them in a Land Raider or if your feeling brave try walking them up to your opponent with other similarly loaded squads for a 24” line of death…
Grand Master 2: 205pts
Psybolt ammo
Falchions, M/Crafted
Blind grenades
Digital weapons
Dump this guy with a squad of 5 in a LR Redeemer / Crusader and watch your opponent quake as you roll up to him with AV14 support…LR too costly then why not be brave and try the chimera, it may not have the firepower but remember you can fire those psycannons out the hatch. 
Grand Master 3: 190pts
Psybolt ammo
Blind Grenades
Digital weapons
3x Servo skulls
Lay down the servo skulls at the start of your game and use them to limit your DS scatter then hope your guys all rock up together… feeling even fruitier?  Drop the servo skulls and slide this guy into a unit of 5 ghost knights and Mordrak and deep strike them in near to your opponent…guaranteed to scare any opponent IF (and it’s a big if) you survive the ensuing torrent of fire.
Conclusion
So there we have a few different combinations for the Grey Knight Grand Master and some suggested situations (some crazy some more serious) for you to try them out in. I really love this guy he’s a CC machine with awesome shooting skills and although the kit he can have isn’t the largest of lists it is very effective at accentuating what he does best, however if like me you’re going to try an all troop terminator army then the Grand Strategy ability can become a little redundant making the Brother Captain or other HQ choices more viable options.