Well, I was originally writing something about some different ways of looking at the issue and needing clarification from CS or the Errata, but I tossed all that out when I saw the below.
This clearly states that when using a Heavy Thrown weapon you are making a Ranged Basic Attack, not a Melee Basic Attack with a special range property like some kind of super-reach. This is important.
No one is claiming this to be the case. This is not relevant to the argument.
Then take a look at p287 of the PHB for the power description of a Ranged Basic Attack. The description has the "Ranged Weapon" keyword only, nothing else.
Incorrect. It does not have the 'Ranged weapon' keyword. '
Ranged weapon means it has the
Ranged attack type with a range of 'weapon' which means something specific. Notice: the weapon is not bolded, but it means that you fill in that blank with a parameter of the weapon. Other attacks have a specific number in squares here. Are you saying that eldritch blast you are attacking with a ranged 10? Of course not. You are not using a ranged 10. You are using a
Ranged 10 power, which means it is Ranged, and that it has 10 as its range. The second part is a parameter, not a keyword.
Below that is the line "Special: Weapons with the heavy thrown property (see page 216) use Strength instead of Dexterity for attack rolls and damage rolls." Since this special line is under the power description that includes only the "Ranged Weapon" keyword, this means that when attacking at range with a Heavy Thrown weapon it is only counting as a Ranged Weapon in that attack. This would be a specific rule that is saying that a Ranged Basic Attack with a Thrown Weapon is counting it as a Ranged Weapon.
This is a fallacy. You are using a melee weapon that can be counted as a ranged weapon when used with Ranged powers. This is a completely different thing. Regardless, it does not matter if the weapon is counted as a Ranged Weapon. It does not cease to be a melee weapon. At no point is it forbidden to be used in Melee attacks.
That's pretty cut and dry, and pretty much invalidates any possibility of Intelligent Blademaster applying to Heavy Thrown weapons. It's quite clear that when you're using the thrown weapon in a ranged attack, it counts as a ranged weapon only. There is no specific rule dealing with melee weapons making ranged attacks, only with Heavy Thrown weapons functioning as a Ranged Weapon when making a Ranged Basic Attack. This might be something to look into suggesting an Errata for, but until one comes out, I don't see any way to apply a bonus for melee weapons to a ranged weapon, which is what you're using when you're attacking with a Heavy Thrown weapon.
But when does it -stop- being a melee weapon? No one is claiming it's not being used as a ranged weapon. No one is, in fact, claiming that you're not using Ranged Basic Attack. In fact, that's sort of the point. You -are- using Ranged Basic Attack, which is a basic attack, and you are using a melee weapon to do so. You are therefore using a basic attack with a melee weapon, and you can therefore replace Strength with Intellegence.
Please note: Shuriken -are- a ranged weapon with the light thrown ability. If they had a ranged weapon with heavy thrown, you would not be able to use it with Intellegent Blademaster.
No one is arguing that you're not using the heavy thrown weapon as a ranged weapon. No one at all. What IS happening is the argument that the weapon never ceases -being- a melee weapon. Intellegent Blademaster does not care about the -kind- of attack you make, only about a quality of the weapon. It asks 'Is this a melee weapon?' There are no heavy thrown weapons that are not melee weapons, therefore Intellegent Blademaster applies to all basic attacks made with them.
If it was supposed to mean 'melee basic attack' it would say 'melee basic attack' just like -every other instance- of melee basic attack-altering properties do.
Ask yourself this.
If you use a one-handed weapon with versatile, using it two-handed, and you have the one-handed weapon talent, do you get the +1 to hit? Yes. It does not stop being a one-handed weapon.
If you have Weapon Focus: Heavy Blade, and you use an Implement power, do you get +1 to damage? Yes. The heavy blade does not cease being a weapon even tho it is used as an implement.
If an enemy incurs an opportunity attack from you, and you have Heavy Blade Opportunity, and you score a critical, if you are using a kopesh, do you also get to apply Deadly Axe? Yes. The kopesh still functions as an axe even if you use it as a heavy blade.
In every case, the ruling is that weapons do not lose their fundamental traits simply because they are used for other purposes or they are used in different ways.
The -general rule- is, therefore: Weapons apply all their properties at all times. There is no such thing as the exclusivity of properties of accessories. Some items can have seemingly contradictory properties, like staffs or light blades being weapons and implements.
There exists no specific rule that makes an exception to this.