Can a hybrid character replace his only encounter attack power belonging to one of his classes?

Question

Assume a Paladin|Swordmage with Cha and Con dumping Int, or a Driud|Runepriest with Wis and Con dumping Str. As the relevant ability is very low, it would make sense not to pick any power from the secondary class. However, hybrid rules say you must.
Is there a way around this?

I do not think Reserve Maneuver or multiclass power swaps work, but I am not sure.

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Background:
Why would I want to make a hybrid, if do not plan on using its powers?
The answer is for a class feature. An Assault Swordmage can almost guarantee an MBA as an Immediate Reaction every round, and Serene Blade Runepriest can give a decent AC even for a Swarm Druid.

What about other types of powers from the secondary class?

• Utilities mostly do not care about your primary ability modifier
• Quite a lot of daily powers have so great effects that you do not really care about hitting
• At-will powers are just lost unfortunately

Answer 1

You're mostly stuck with at least one power in each category from your hybrid class.

[I]f you have at least two powers in the same category (at-will attack, encounter attack, daily attack, or utility), at least one of those powers must come from each of your hybrid classes. For example, if you have two encounter attack powers, one of the powers must be from your other hybrid class.

Even if you later change your powers through retraining, power swap feats, or some other means, you must retain at least one power in each of these four categories from both of your classes[.]

-- "Gaining Additional Powers", Player's Handbook 3 pp. 135-136

That's pretty ironclad, at least as far as multiclassing goes. In the build cases you've detailed, where you dumpster the primary ability of one of your hybrid classes, you're best off planning in advance to see what encounter and daily from the hybrid are either non-ability dependent or have significant Effect lines.

...mostly.

However, using Reserve Maneuver to forgo recharging your alternate-class encounter power is fine in this case, though you must spend it first. Reserve Maneuver doesn't permanently exchange one of your powers in the way that a power swap feat would; rather, it gives you an extra option for a power to recharge. You still have the required one encounter attack power from your hybrid class, you're just not recharging it.