⚔️️ An archer ambushes you from higher ground out of reach, what do you do?
The initial hit would have to be taken with reflex. Any mercenary who’s been at it long enough eventually develops a bubble around themselves where they can sense something intruding, and it’s up to them to retaliate to them. Soren, for example, can force a wind-assisted dodge subconsciously, or even with his limited strength, can deflect arrows with the dagger at his thigh.
Ike is no exception-- due to experience with Shinon, that specific sound of whistling air has his first reaction to deflect and second to dodge. The follow-up is also instinctual, so he’ll draw his hunting knife and snap-throw it at the direction it came from if it was a projectile.
Throwing the projectile is something that won’t connect-- the real objective here is to seek cover with the bought time, likely rolling into it. If there isn’t any cover, he’ll take evasive action, keeping his movement unpredictable and crouching to face the shot with his armored side, cape held to obscure his profile a bit more.
Then, presumably, he sees the archer.
One of the weaknesses that Ike quite rather notably has is that he can only advance at the pace of an infantry unit. He’s chosen not to carry a heavy shield which would be extremely useful here, so there’s no way around it-- he has to suck it up and approach manually, deflecting with Ragnell held in guard position and dodging as he goes.
As for how he does so, however-- that’s his choice, and also dependent on how good the archer is. If the archer’s like Shinon, then there’s absolutely no point adding a third dimension: He’s better off staying low to the ground, getting cover, and running in a random pattern as you approach. If he can, bring the cover with you, but make sure that it’s possible to peek out from it.
Specifically: if the archer is Shinon, there is no point in bringing logs of any kind. Shinon’s strength is longbow-grade, and he can easily just punch through both the log itself and the person behind with a well-placed arrow. Only stone slabs themselves will do, or pure metal. Ike might also pick up an armored corpse from the battlefield and charge with it, or someone’s shield. Alternatively, Urvan works as well.
The good thing about Shinon, however, is that he probably... prides himself on his arrow accuracy too much? Which to say, he’s not going to be using modified arrows with bombs.
Fire arrows and poison-bomb arrows are a different beast. If there’s only a single archer, Ike doesn’t really have to care too much about them-- he can dodge them with ease since there’s no saturation, and the bomb or modifier will slow down the arrow speed and accuracy to the point where it’s going to be a terribly poor shot. If there’s enough of a boom attached to the arrow, then he’ll make an attempt to roll with the force of the explosion, or leap with it.
On approach, he’s likely to start skipping rocks at the archer, hoping to nail or flinch his aim. This is a cover for any potential tomahawk or extra daggers he’s carrying as well: after getting used to the pace of Thrown Rock, they probably don’t expect a dagger thrown alongside it or the next time they pop up to take another shot.
If he has Ragnell, he has another option outright, and will retaliate by striking back with the shockwave that Ragnell can produce.
Once close enough, Ike will attempt to scale to the archer. He’s an adept wall-climber, and can leap very, very high if he wants to-- he’ll be chaining both to try and reach. He prefers to do this from below, and if possible from obscured sight of the archer.
Then is the perch the archer is on: If it’s solid, there’s nothing he can do about it-- clamber over and chase them down. If it isn’t, however, he can attempt to crumble the perch by clinging to it and focusing on Ragnell to force an explosion with its condensed shockwave (Eruption), and rushing through the path made there. Alternatively, he can also just use shockwaves to cut swathes through the platform, ‘grounding’ his slashes so they conduct through solid earth instead to wrap around a ledge. Finally, he can directly smash through the cover with Aether itself, first by throwing Ragnell through and brute-forcing his entry leap after.
If the archer is of subpar quality, Ike will put his entire effort into simply sidestepping and deflecting the arrows with the sword. He might throw one back for fun? Hey-- It’s good practice...
As a rule of thumb, if Ike does get shot with something, he generally doesn’t remove the arrowhead and will only break the shaft, because it’ll cause him to bleed heavily. Dealing with that is a matter when he can make or get someone to staunch that issue.