This is a specious argument. Each implement type (including weapons) has it's own list. Saying that weapons have different enchantments doesn't make them any different from any other implement.
Let's follow your logic for a moment: the question being whether implements and weapons are the same thing. You are confronted with a difference between implements and weapons (namely, usability of properties without "wielding" them). You are also confronted with another related difference (the enchantments which provide said properties). You suggest this difference doesn't actually make them different. Then you suggest that since they aren't different, this difference doesn't exist!
Well, that solves it: since there's no difference, there's no difference.
If one permits implements to grant passive benefits (like +1 to defenses) when held but unusable one must logically grant it to weapons as well to avoid penalizing weapon-focused characters.
Penalizing weapon based characters simply doesn't come into it; there's a whole bunch of other rules with also don't work identically (just to start with, the damage dice, proficiency bonuses and feats available; the powers that use them, the class features of the classes that focus on them, etc.), so you can't just assume that some (fairly tiny) balance difference like this isn't actually balanced by anything else. In fact, due to the variety of weapon-specific feats+items, the common stance is rather that weapon users have a small edge, resulting in the fact that it's somewhat attractive to use weapons as implements when possible.
In any case, weapons are not a type of implement. They may be similar, but they are not identical - as, for instance, in this case (but see below). There are also various other relevant distinctions
- You can use a weapon you are not proficient with to attack. You cannot use an implement you are not proficient with. Using a weapon you aren't proficient with means losing its proficiency bonus (p. 219)
- Weapons have specific damage dice; implements do not.
- Weapons differ in terms of proficiency bonuses and range (or reach and other properties). These modify the usage of most weapon powers. Implements have neither.
- Being proficient with a weapon means you can use that weapon equally well for Weapon powers that you know of any source and of any class (barring a few explicit exceptions). By contrast, implements are tied to classes. If you learn a power from another class, you cannot use implements from your primary class (that aren't also implements of your secondary class) with powers of that secondary class even if they are implement powers.
Now, though weapons aren't implements, it
is true that
this distinction (concerning properties) isn't very consistent: a better reason being because some PC's can use weapons
as implements. What to do with such characters? Well, the
rules seem to suggest that as long as you
can wield it as an implement, it's properties are active when merely held. Yes, that's pretty nasty - I think we can assume that this wasn't a focus of the design team.
But let's not exaggerate the problem. It's surmountable. Also, weapon properties tend to only affect powers delivered with the weapon (again according to the AV). For such properties, there's no conundrum; who cares if the property is active on a weapon that isn't wielded if it only affects attacks made with it - there aren't any such attacks.
In any case, some properties don't look to be written with the "you must wield it" rule in mind anyhow. For example, a brilliant energy weapon gives off bright light unless covered and sheathed. Presumably, that property is active even when it's not even held, otherwise the "covered and sheathed" part is a little pointless. The vast majority clearly affect attacks (made using the weapon), and there's no issue of them being active or not when held; it just doesn't matter. Others clearly apply at all times - again, there's no issue with weapons vs. implements here. Only very few weapons really have properties that might have an effect when not wielded in the first place.
What does wielding as used in D&D mean any how? It's not even clearly defined, but it looks to be attack related; you need to wield a weapon to attack with it. Most properties are also attack related. I think it's quite reasonable to assume the AV section is written in this context - i.e. that the requirement to be wielding a weapon (i.e., to be able to attack with it) applies specifically to those (most common) properties that affect attacks. In short, they're explaining not a generic limitation of properties, but rather the context within which you should interpret them. If a property speaks of affecting an attack somehow, the assumption is that you are using that weapon for the attack.
To wrap it up:
- Weapons are not implements (or vice versa)
- Implement properties are active even when merely held
- Weapon properties are active only when wielded - but there are properties for which this apparently doesn't hold; they don't make any exception explicit, but it looks obvious there should be one. This rule not on stable footing.
- The system isn't water-tight anyhow; weapons can be used as implements, so for some (rare) properties that actually affect things other than attacks, there may be some confusion.
- For the vast, vast majority of cases, there won't be a problem, and for most of the remaining cases, the problem will be minor; whichever way the DM rules (on weapon properties that affect non-attack actions when used as implements by PC's that can do so) will be fine.
