Is it worth it to invest in those perks, extra bleeding for axe, critical damage for swords and the ignore armor for maces???
And what's the best of the three???

Depending on the weapon you use it could be worth it but of the 3 extras mace is probably the best as it eliminates 75% of the armor that heavily armored enemies have and makes crunchy enemies squishy... Axe one I wouldn't really take at all and sword one I never worried about because it was a percentage chance, and as an assassin type I refuse to rely on luck to take out my enemies... So in my personal opinion the extra perk is only useful if you are using maces...

If you are more of a purist warrior however the sword one would be quite useful as, while it won't go off every time it will be noticeable and could end your larger scale fights noticeably faster...

I found those particular weapon type perks to be sort of meh.The mace one probably makes the most sense , giving them a way to make up for a slow swing time.The sword critical chance is kinda cool , it makes a crit sound every time it procs , but not really game-breaking.The axe ...... situational.It doesn't work on things that don't bleed.However, if you play a hit and run type guy maybe it would change things like smack the living crap out of a bandit leader then run like hell turn and finish him at lower levels.But I'd say goin right up the tree for standing damage and a charge effect is what I'd wait for.And in the meantime spend points in survivability or whatever else you're into until you have the skill.