Yes, though I think it displayed both Goku's courage and Goku's power as well. Goku's approach of letting Trunks attack knowing he'd stop caught Trunks off guard and likely affected his judgement on Goku. Though Trunks was also surprised by the fact Goku could stop all those slashes, emphasizing that such sword cut Freeza down. It's true that Trunks was holding back, but I think that even accounting for the fact he was holding back, a display of strength by parrying/blocking all the attacks with a finger filled with chi is also a strength display that caught Trunks off guard. Even though Trunks didn't go all out, I'd say that strength and pressure used to attack Goku likely would have been enough to kill Freeza as Trunks pointed out that such sword cut Freeza down easily --- with Goku pointing out that Trunks wasn't going all out imo not necessarily challenging the notion that the sword and Trunks' strength used then could cut Freeza down, just that Trunks was more capable than that still, speaking more on Trunks' overall abilities rather than the feat of killing Freeza with that. In my opinion, it'd be off place to point that out if he weren't using strength capable of managing such a feat, that he brought up to make a big deal of Goku defending from such attacks --- defending easily from attacks that could cut down Freeza!
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I'd say Goku's strength when defending from the sword was also tied to Trunks saying Goku was even greater than the stories. I think it'd be a mix of Goku sensing no malice and therefore not defending himself firstly, showing a unique and knowledgeable approach... And later on, displaying his strength by stopping all the attacks with his finger filled with chi.
IMO, Trunks expected Goku to be around his level, more or less... And Goku turned out to be even stronger than that, though by a not considerable margin --- by a slight to noticeable amount --- more or less the improvement Goku had in the time he was on Yardrat. Goku focused most of his time there mastering the Shunkan Idou, but he also ought to have dedicated some time to hone his strength, I would imagine, as it doesn't seem that mastering the teleportation was all he did there. He said that at the start, transforming at will was very difficult, but that with time it became easy, so we know that at least some time was spent in getting used to SSJ and making that transformation easily controllable. I think this few moments off from training teleportation might explain some improvement, albeit not a big or drastic one, just one comparable to, say, Freeza's when enhancing his body through cybernetics... Then still maintaining his superiority the same... While if he stayed at 150,000,000 exactly, it may have been a drawn out battle vs Mecha Freeza, one in which he would win after a decent struggle, but would likely lose if Freeza and his father attacked him together.
Yes, I agree they had different mindsets when fighting Freeza. Though, I would say that Goku's merciful nature came more at moments he could kill Freeza without giving Freeza the opportunity to use full power. He seemed to be intended on killing Freeza when he caught on Freeza needing some time to power up to 100%, to which Freeza desperately Kiai'd him using 70%... And then he was charging at Freeza once he was powering up to 100%... But changed his approach midway --- stating that he wants to beat Freeza at his best, so Freeza wouldn't have regrets as a warrior. I think this may be when his nature of being more lenient and merciful came at play... while he could have quickly dispatched of Freeza there without giving him the time. When Freeza was at 100% and they battled, then I see Goku battling Freeza with all he had. He had the upper-hand clearly and it seems Freeza's best moment was when using his shield attack and getting Goku off guard by getting out of his KMHMH trajectory and hitting Goku with all he had, which took Goku some time to come back, but still had little effect. Besides that, he could get some hits on, but Goku's advantage was clear --- not saying you disagree with this, I'm just pointing it out for clarifying how I see the battle. So to me, when they were both at 100%, it was a battle portrayed in a way that Freeza could get something done, but at the end of the day, Goku was just ahead of him and could showcase his superiority in a noticeable and apparent fashion --- he was simply noticeably ahead Freeza.
I think Trunks may have found himself in similar problems if he allowed Freeza to power up to 100%, but at the end of the day, despite that not being a one shot KO like it was, he'd outdo Freeza in a dominant fashion, though Freeza would put up a resistance, but one from a losing side that would be made apparent... One in which he could make Trunks put in the fire a little and battle him, but one in which Trunks' advantage would become apparent without that terrible tough time... Which I think that, on top of the power advantage, would be made still more one sided due to Trunks' sword... Which while still not the main source of his powers, was an extension of his strength, potentially stretching the gap a little more still.
I think that statement from 17 would just imply that his less than half power was above Gohan from 1 year prior. After 1 year, it seems Gohan built strength enough to at least defeat that level future 17 used to mess him up...
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It seems Gohan's training left him in a position to outdo the level 17 used vs him last time, as in the following panel, 17 stated "our turn? Heheh. Sorry to disappoint you, but I didn't even use half my power last time...." ... To which Gohan was like !! What?? --- and then 17 proceeded to attack him. Before that, Gohan knocked Trunks out saying that if he died there too, there would be no one left to protect the Earth... So yeah, I agree that it seems Gohan was going there prepared to die. I think this duality between him going there prepared to die and saying he'd defeat 17 might be he being prepared to a possible scenario that may very well happen --- him dying --- and then KO'ing Trunks so that in case this very possible scenario happens, their hopes aren't all lost. Like when a fighter knows that they have the ability to win a scheduled fight against their opponent, but also knows that despite knowing they have what it takes, they can also very well be defeated. Or, perhaps, the fact Gohan knows he was facing both androids... So even though he had the power to defeat 17 based on what he had displayed last time, knowing that there is 18 too, and that with 17 alone it already wouldn't be an easy battle, turn the full result as a hopeless battle to him as for surviving. One in which he can take them individually, but at the end of the day, their team up is too much for him --- which may happen even before he can finish 17 if 18 sees this would happen.