It would make sense to me that you would have to. You gain the benifits of ghost touch by using the weapon, you gain the benifits of the various burst weapons by using them. Yeah yeah, I know their are exceptions (like the luck blade bonus), but these exceptions are spelled out.
Well, some benefits apply when the weapon is used with an attack action (like Defending). Some benefits apply to 'the wielder' (like the protection from fire of a Frost Brand). And some benefits apply to 'the possessor', like the luck blade bonus.
The Luck Blade gives its bonus while sitting in its sheath.
The Frost Brand gives its protection while in handy ready for action.
The Defender gives its AC when used with the attack action, because the Sage said so.
If the Frost Brand required the attack action to function, you'd have the weird situation of someone walking through the burning field with his sword that magically keeps him from being burned in hand... that doesn't work unless he moves at half normal speed, while spending the remaining time imagining slicing at someone.
The Speed enhancement is something that functions for "the wielder", and someone could, holding their Bow of Speed in one hand, cast True Strike, and then as a free action switch their bow to "ready mode" per the recent Sage longspear ruling, at which point they are "the wielder".
However, the Defending property is also described as functioning for "the wielder", and we know how that one works.
So there's room for either interpretation.
Since the Speed enhancement is based on Haste, and Haste allows one to cast and attack in the same round (hell, Haste at the moment allows one to cast and Full Attack!), there's support for that argument. But flavour-wise, it also makes sense that the Speed property only allows an additional attack
if you make an attack in the first place.
-Hyp.