Kensai sharpen the blade

[Aaedimus]

Does the kensai sharpen the blade ability stack with already magical weapons?

I don't see anything in the description stating non-magical weapon

[Grear Bylls]

Does the kensai sharpen the blade ability stack with already magical weapons?

I don't see anything in the description stating non-magical weapon

No. It says it won't work with weapons that add to attack or damage rolls. If the weapon doesn't do that, yet has another bonus, like another die on hit, it would work

[Malifice]

Does the kensai sharpen the blade ability stack with already magical weapons?

I don't see anything in the description stating non-magical weapon

It specifically states it doesnt stack with magic weapon bonuses.

That said, there are tons of magic weapons that dont give bonuses, and instead do other stuff.

[MeeposFire]

To be pedantic it says it will not work on a weapon that has a bonus to attack AND damage. Not sure if that ever comes up as something to be taken advantage of (are there any weapons that give a bonus to damage or hit and not the other on a direct +X type?) but it is there.

Also depending on the wording it might be technically illegal to use it all with a weapon that gives a bonus to hit and damage (emphasis on might) but a lenient (and frankly I believe this to be fairly reasonable as well) DM would probably allow you boost your +1 long sword to being a +3 long sword if you spent 3 ki to do so (so it is not stacking but overlapping and I would think that to be fair). The wording might allow that already but I cannot remember for sure since it could just be one of my lesser used house rules coming back influencing my memory.

[Speely]

Would work wonders on a Flame Tongue.

[CircuitEngie]

To be pedantic it says it will not work on a weapon that has a bonus to attack AND damage. Not sure if that ever comes up as something to be taken advantage of (are there any weapons that give a bonus to damage or hit and not the other on a direct +X type?) but it is there.

Also depending on the wording it might be technically illegal to use it all with a weapon that gives a bonus to hit and damage (emphasis on might) but a lenient (and frankly I believe this to be fairly reasonable as well) DM would probably allow you boost your +1 long sword to being a +3 long sword if you spent 3 ki to do so (so it is not stacking but overlapping and I would think that to be fair). The wording might allow that already but I cannot remember for sure since it could just be one of my lesser used house rules coming back influencing my memory.

"This feature has no effect on a magic weapon that already has a bonus to attack and damage rolls."

The +1 Longsword is unaffected by 3 Sharpen the Blade ki points. Not that it's an unreasonable change to allow given how easy it is to have a non-magical weapon on hand to sharpen.

[Malifice]

Would work wonders on a Flame Tongue.

Or a weapon of warning, or life stealer etc.

[MeeposFire]

"This feature has no effect on a magic weapon that already has a bonus to attack and damage rolls."

The +1 Longsword is unaffected by 3 Sharpen the Blade ki points. Not that it's an unreasonable change to allow given how easy it is to have a non-magical weapon on hand to sharpen.

That is what I thought. It was one of my houserules that allows you to boost a +1 sword up to +3 using 3 points I would agree with anyone saying that the idea is reasonable to allow even if it is not actually allowed by the rules.