The keris is indeed a mystical weapon which traditionally symbolises, power, authority, dignity and sovereignty of the Malays as a race.
One version has it that it originated from Sri Purba Sakti, a Hindu mystic who spent most of his live as a hermit in one of the mountains in what is now west Java thousands of years ago. He was challenged in a dream to come out from his hermitage to lead his fellow Malays who were then Hindus.
The keris was given to him to symbolise authority and the responsibility that always comes with the former. It was a nine 'lots' keris with the handle carved in the form of a dragon. This was to remind him that his authority came with a heavy responsibility.
The dragon symbolises both wisdom and power whilst the nine 'lots' represent nine levels of punishment that would be meted out against him if he abused the authority
The keris is, therefore, a very sacred regalia of the Malays which is not meant to be unsheathed and displayed at will. It was only in the later years that it was used as a weapon for killing enemies or during an amok episode. The keris is best known as used by the Bugis during the time of Hang Tuah.
On whether Umno Youth head Hishammuddin Hussein Onn had used the keris provocatively or otherwise would depend on whether the Umno general assembly was a solemn occasion.
Personally I do not think it was as the assembly was conducted like a mass 'boria' session with speakers spewing raw emotions and invoking racial sentiments rather then giving words of wisdom and proposing positive plans and strategies for the improvement of the Malaysian community.
It was more of an 'amok' style compounded by the arrogance of the high and mighty. I fear that Umno will be swallowed by the dragon.