I can agree that monk is a little underwhelming in some regards, but I certainly don't think it can't be strong. I think some part of how it seems that not an awful lot past power up, kaduha and other staples see use is that it's a very common sub class rather than main.
One thing I agree on 100% though is the ki awoken stuff, as well as some of the suggested changes from op and comments. As it stands right now, ki awoken is comically bad, utterly unusable even with gimmick builds that are built for it. This really sucks when it's one of the monk's signature skills and is thematic and flavorful as hell. To put it in perspective without getting down into the nitty gritty with damage numbers and diminishing returns, in order for you to just break even on value when using it, you need to do additional damage and/or get additional value out of the extra ki, etc equal to the 3m you spent plus the % of hp you're losing every turn. Even for gimmick builds that choose their stats to deliberately avoid diminishing returns on the stat boosts, it's very difficult to just break even on value using it for 1 turn and then turning it off before the 10% loss. Anything past that, anyone and everyone is just worse off for using it. And we're talking just ending up no better or worse off for using it here. Actually gaining anything by using it, as far as I can tell anyway, is 100% impossible in its current state.
I think increasing damage amount by ki % while active is the only suggestion I've seen that could make up for the heavy hp cost when you also consider that you kinda need to make up for the 3m you spend on activating it. The suggestions of adding extra effects to other monk skills probably comes close. The only other suggestion I could add is to keep the hp loss effect, and possibly even the same numbers behind it, but just substitute it for fp instead. It still limits how long you can keep it active and doesn't allow for any mega fp pool shenanigans if it remains a percentage, while also making it accessible for those without a lot of fp. Making some portion of the boost ignore diminishing returns is also a really good idea, as that majorly limits its usefulness for most if not all people even ignoring the inability to get any value out of it as is.
One thing I agree on 100% though is the ki awoken stuff, as well as some of the suggested changes from op and comments. As it stands right now, ki awoken is comically bad, utterly unusable even with gimmick builds that are built for it. This really sucks when it's one of the monk's signature skills and is thematic and flavorful as hell. To put it in perspective without getting down into the nitty gritty with damage numbers and diminishing returns, in order for you to just break even on value when using it, you need to do additional damage and/or get additional value out of the extra ki, etc equal to the 3m you spent plus the % of hp you're losing every turn. Even for gimmick builds that choose their stats to deliberately avoid diminishing returns on the stat boosts, it's very difficult to just break even on value using it for 1 turn and then turning it off before the 10% loss. Anything past that, anyone and everyone is just worse off for using it. And we're talking just ending up no better or worse off for using it here. Actually gaining anything by using it, as far as I can tell anyway, is 100% impossible in its current state.
I think increasing damage amount by ki % while active is the only suggestion I've seen that could make up for the heavy hp cost when you also consider that you kinda need to make up for the 3m you spend on activating it. The suggestions of adding extra effects to other monk skills probably comes close. The only other suggestion I could add is to keep the hp loss effect, and possibly even the same numbers behind it, but just substitute it for fp instead. It still limits how long you can keep it active and doesn't allow for any mega fp pool shenanigans if it remains a percentage, while also making it accessible for those without a lot of fp. Making some portion of the boost ignore diminishing returns is also a really good idea, as that majorly limits its usefulness for most if not all people even ignoring the inability to get any value out of it as is.