The Indonesian or the Malaysian kris called keris like the ones in this photo is not really the same as the Mindanaoan kris called kalis. The difference is obvious mostly in the head and handle design. Kerises usually display Indo-Buddhist designs while kalises exhbit Turkish influences.
Keris came from the Malay word keras-- it means hard, sharp, strict, violent, and severe. Its meanings are obviously about the nature of the sword as a weapon for ritual, war, and punishment. Keris was Anglicized and became creese and later, kris. Merriam-Webster Dictionary listed 1580 as the year kris became a word in the English lexicon. It must be through the European explorations in Southeast Asia that time.
Keris as a word failed to reach Mindanao. I assume that the early Mindanaoans had a different name for their krises then. It must be kali since the sword was brought to the area by the Majapahit Hindus from Java together with the Hindu Statues. Between the two dieties, Shakti and kali, the latter is the one that wields a temple sword. Kali still has to be unearthed today.
Kalis, meaning proof, could not be the original name of the Mindanaoan kris because it was already an existing Malay word that time. Its meaning has no obvious relation/connection to a sword. Kali is more feasible than kalis. In etymology, you go for the nearest relationship, meaning, or concept.
Before the Islamic missionaries arrived in late 1300's, krises in Mindanao were the same as the ones in Java and Sumatra. They had Indo-Buddhist designs of Hindu phoenix and Buddhist dragon. When the Arabs came, the Mindanaoan kris began to evolve and used Islamic elements.
The spread of Islam that time was also the rise of the Turkish Ottomans, who were orthodox Sunni Muslims, the same kind of Islamic faith that can be found in Mindanao today. I believe that the Turkish Ottomans also reached Mindanao. They brought their yatagan swords that influenced the handle designs of krises in the area.
The clean sculptural head and handle of the yatagan was the earliest handle design of the Islamic kris of the Mindanaoan Muslims. The Indo-Buddhist handle was replaced by the Turkish one. In archeology, when it comes to tools, the evolution happened from simple to complex. Compare the yatagan's handle to the kris' of Mindanao.
The Ottomans reached India in late 1300's. It is possible that they reached Mindanao too, particularly sulu. Southern India and Mindanao had a long history of migration, trade, and cultural exchange. That time, the spread of Islam was congruent to the spread of the Ottoman empire in Asia and Europe.
Yatagan did help also in the change of name from kali to kalis. The Turkish word for sword is kilich. Filipinos have no ch sound. Its nearest equivalent is s sound. So, from kilich, the Turkish word became kilis, a local-sounding word.
Kilis would have been the word that would have the same linguistic form as keris. In some Philippine languages and dialects, letters r and l are interchangeably used-- example: dalawa (two) can be darawa and araw (sun) can be alaw. The evolution of the name for kris did not stop with kilis. Kali was incorporated. Thus, the Mindanaoan kris became kalis and has remained the same until today.